All of these are American, or at least I use them:
Sweet: Awesome, Cool, Great
Retarded: Pertaining to being slow or stupid; not meant to be derogatory to mentally challenged. Other words are ReRe and Dumb@55 (not sure what your rules on profanity are here)
Yeah, and I'm the Queen of (insert country): Sarcasm, indicating how unlikely something is. Also, see "when pigs fly" "Once in a blue moon" and "Yeah, Right !"
He got laid out!: used in American Football and Hockey, but general use means someone was hit extremely hard and was flattened the instant they were hit. Interchangeable with "He Got Raped" and "Owned"
Holy Crap! (or your choice of profanity): Interjection of excitement and surprise at something unbelievable, either good or bad.
Go Figure: Either indicates Irony or a decision that fit's a person's character traits, usually sarcastic
Throw it into... : put an object into something, such as a microwave or a stove, or a garbage can (in AE, trash can is used more often)
screwed up: not cool, as in disturbing or not in the right. Also used as phrase, as in "you screwed up"
You dug the grave, now lie in it!: It's your problem, you deal with the consequences.
Balls out: without regard to safety or much of anything else, but focusing at 100%. Used often in sports, as in "He's running balls out towards the endzone"
Putting on the jets: To quickly accelerate to full speed from a stand-still or jog
Top-Notch: The best
Frenchy or Frenchie: Disparaging remark towards the French, but usually used in jest among High School students with recently emigrated French students who have become friends.
I could care less: I don't much care about it, it means nothing to me
I don't care: usually the American equivalent of the British "I don't mind", but can also indicate annoyance
That (color, religion, stereotype, etc of person) dude (guy): In most parts of the United States, this is acceptable as long as the person you are speaking too knows you are not a racist. Pretty much every person of every race I know uses this, it's just a general descriptor to help give a person a mental picture of someone before you give them better details. This is mostly because of the great diversity of the U.S.
Not Worth a Crap: Something so bad it is not worth someone's own feces
All Guns Blazing: Giving Everything they've got at once.
That's (expletive) Metal!: Relates to the music AND the dark, heavy themes, such as death and destruction, blackness and nuclear war, that define Heavy Metal and it's sub-cultural lifestyle
Crank it to 11!: Taken from the movie "This is Spinal Tap", means to take the intensity over "the cliff", or the edge, if you will, to go above and beyond the normal constraints.
Ghetto (Hood): A generally poor area that gives birth to gangs, violence, and some pretty interesting stories from anyone who lives there.
Brit: American equivalent of Yank. (Which I take pride in
)
(insert name) is god!: Not to be taken literally. Means that person is better than every similar person in their category/hobby/job, etc. Usually used for rock musicians
Chillax: Chillout and Relax. Maybe at someone's house or at a beach.
(Ebonics) You Tryin' Me, Cuh!: You're trying to make me angry. Usually followed by threats for a fight which usually never happens.
Pip Pip Cheerio: Simply making fun of British Recieved Pronunciation
Oh yeah? Well (insert noun) makes (another noun) look like (something small or large, usually somehow related): I.E. "Well, the Xbox 360 makes the Playstation 3 look like a Gameboy Color
I'll add more later. Goodnight to some, Goodmorning to others
For example, I used to always say 'dam' but instead, nowadays i say 'dang' (an american's influence lol)
i don't use this word but loadsa brits do 
