fuck. May or may not be capitalized.

What the F is that?
F me.
F this shit.

1. Short for "fuck."
2. A shitty grade.

1. F you.
2. OH NOS!!!! TEH F!!!!1

*assimilated*

1. the sixth letter of the alphabet, pronounced "eff"
2. A very very very very very bad grade, which usually prompts disciplinary actions by parents of young children.
3. the last letter in the slang acronym WTF, which is commonly used often by n00bs, or used occasionally by l33ts to indicate surprise, shock, or rejection towards something.

1. F is a letter, use it.

2. I got an F on my Physics test, looks like father is going to tie me to that tree in the front yard and flog me until i'm sunburn red.

3. WTF????!!!!!11111

Commonly used at the beginning of words to imply that you are extra (whatever the word is).

fatass: dude im so fungry
nice friend: wtf?
fatass: fucking hungry!
nice friend: didnt you just eat a four course meal only minutes ago?
fatass: yea but im still fungry. take me to golden corral!
nice friend: if you keep eating this much youre probably gonna fie.
fatass: wtf?
nice friend: FUCKING DIE jackass

other commonly used f words are, fored, firsty, and fired.

An abbreviation for the terms bf or gf (boyfriend or girlfriend) but more ambiguous in the sense that it can mean either one. It means 'friend' but in a romantically inclined way.

"Have you met Chris's new F?"
"What was her name again?"
"Josh."
"I thought it was a girl."
"Apparently not."

F is an exclamation used in place of a swear word when one loses the game.

Jessy: Danielle, you lose the game!
Danielle: F!

a felony

"If you caught a felony, you caught a F."
-Big L, Ebonics