The point is when one watches a lot of British pop-culture, one notices a lot of British slang. After a while it doesn't really confuse you any more. You get what they mean, even if they feel compelled to say it in frustratingly un-American ways.
But after comprehension has been mastered you realize that the British seem to have a very different concept about what makes for good slang than us Americans. A first reaction is usually the old nativist stand by, "my country's way is best!" But after putting a little more thought into it, I realized that there are some real trade offs here. In some ways British slang is totally misguided and inferior to ours. And in other areas it totally kicks our ass.
In the interest of helping my nation examine this complicated matter to rise above the challenge and make our own slang clearly superior, I give you a healthy slice of Pros and Cons to British slang as compared to American.
Pro: Mates This is a nice way to refer to your friends. It implies people you actually enjoy being around rather than just people you kind of know. American slang doesn't handle this distinction as nicely.
Con: Fag The worst slang term for something you put in your mouth ever. It's supposed to mean "cigarette," but that is so NOT the image it conjures up.
Pro: Snog A word for making out that sounds a little comic and indecent which it so often is. Good slang terms sound like what they mean, and this one works on that level.
Con: Tea It doesn't just mean the beverage. It means dinner. Or supper. Or, you know, whatever you call that final meal of the day where you live. This one is needlessly ambiguous and causes all to many Americans to miss dinner when traveling abroad.
Pro: Bugger A nicely happy little curse word, which is an aspect of cursing American slang has never quite mastered.
Con: Bum Why would you want to compare a derriere to a dirty vagrant unless you meant it as an insult? And this one isn't considered an insult, so just lose it.
Pro: Cheers It's kind of the British version of "Aloha." It can mean "Hello," "Goodbye," "Thank you," "You're welcome," or darn near anything else. It's the Swiss Army knife of slang. And works WAY better than our attempt at inventing this (see: the Rise and Fall of "dude").
Con: Uni It's supposed to be a cute abreviation for "University." We use the word "college" for that. Ours is better because it doesn't sound silly.
Pro: Wanker Another terrific curse word that sounds not so bad at first, but with implications just as rude as you might intend.
Con: Blow off This is one of the British expressions for farting. The people who developed the classic term "breaking wind" for that activity really let us down this time. Needlessly confusing and vague.
Pro: Prat Continuing the theme of superior British cursing, "prat" sounds nicely insulting wheter or not you know what it means.
Con: Dickey You'd think people so good at creative cursing would have spotted the nasty implication here. Alas. "Dickey" is a way to say you're feeling sick. I'd stick with "I'm feeling sick," personally.
Pro: Twat Before we leave behind the theme of great British cursing, "twat" deserves a mention. It makes a rude reference to a part of the female anatomy that American slang stumbles around by either going too silly or WAY too rude.
Con: Pissed In Britain this means you're drunk. In the U. S. it means you're angry. How we took this same word in such completely different directions baffles me. But as it sounds a little nasty when you say it, ours is better.
Pro: Dodgy Do we even have an American slang term for "untrustworthy"? Why not? Very useful. Plus this one evokes the image of evasiveness which kind of implies what it means.
Con: Pussy For Christ's sake, do NOT name your cat after... I mean respect other people's standard slang at least enough to avoid... Oh forget it.
Pro: Dishy Yum, yum! This is a useful and playful term for calling someone attractive in an implied "wink, wink, nudge, nudge, what I'd like to do with them in bed" kind of way... only fairly polite. I know... sounds like a contradiction. American slang can't pull off this kind of stunt.
Con: Zed It's the freaking letter Z. Zeeeeeeee. It doesn't need an "ed" sound. It works just fine as it is.
Pro: Duffer You say you have a word for a person or thing that is useless trash? And you make it sound polite enough to drop in normal conversation? I'm sold!
Con: Biggie Ahem... do you really need a special term for your child's poop that doubles as a term for an erection? No, you do not. Even if you think you do.
Pro: Gen up A quick & easy way to say "I'm going to research this topic." I could use this one a lot at work. It would save me, like, 6,592 syllables per year.
Con: Bob's your uncle I actually have an uncle Bob, you know. He even reads this blog now and then (quick aside: Hi Uncle Bob!). And now I find that the British use this phrase to mean "and that's it." It doesn't even make it shorter, and needlessly confuses those of us with actual uncles named Bob. And why give the French yet another item to claim snooty superiority over (see: voilà)?
Pro: Nick A useful term for stealing something. Or at least taking something without permission. It also rhymes with "quick" which makes the term sound fast and sneaky just like it should.
Con: Bomb To the nation that survived the Blitz you'd think this would be a bad thing. Nope. To the British this can mean something went really well. Did they even think this one through?
Pro: Potty You have a new application for the word you use to toilet train your child? And it's a mildly insulting term for "crazy"? That's a keeper.
Con: Dog's Bollocks Despite clear evidence to the contrary, this one is a compliment. In fact it's a big compliment. If someone finds a dog's naughty bits all that attractive it's really something they should keep to themselves, not standardize in their language.
Pro: Redundant This is how the British say "laid off." It's not so much how terrific this term is as how awful ours is that brings the mention here. We have a slang term for "laid" that leaves one extra disappointed when we're "made redundant" in our own verbiage.
Con: Fanny We use this word to mean someone's bottom. It's a pretty good word for that. The British use it to mean a woman's bosom, where it is decidedly inferior to slang terms like knockers, hooters, rack, gazongas, and sweater puppies. UPDATE: Well I bollocksed this one up. Learned Foot points out this refers to another portion of the female anatomy. Wink, wink. That's actually pretty good.
Pro: Shite Did you realize you could just add an "E" to the end of "shit," mean exactly the same thing, and yet now it's alright to use in polite company? I didn't either. The British have a genius for this kind of thing.
Con: Knock Up To the British this means wake someone up. To us it means... something very different. I'd go back to "wake up" if I were the British to avoid a terribly confusing and embarrassing international incident.
Any more anyone else would like to add?

Connish: Welcher: As in the US, someone who skips out on a debt. And a Welshman.
For clarification, 'Tea' is for teatime, not the last meal of the day. Teatime is a flexible moment in time but usually falls late afternoon between lunch and dinner; the exact time depends on personal preference but 4pm is good estimation. None of this information can undo your essential observation that the term 'tea' is, in fact, an antiquated load of old tosh.
As for the drink 'Tea', never, ever, be heard to criticize this revered brew within earshot of an Englishman. Empires were built on tea, and a hot sweet cup'o'tea solves every known problem ever experienced by a Brit, including sudden and involuntary decapitation. Just sayin'.