Word all too often used by Americans to connotate a feeling of apathy. The fact that it's used in almost every sentence is not as alarming to many as it should be.

"They bombed a foreign nation without cable TV. Millions died."
"Whatever. They're making another Temptation Island."
"Sweet."

Used in an argument to admit that you are wrong without admitting it so the argument is over.

Man, whatever.

Passive-aggressive behavior at its most eloquent.

She: "If you leave me, I'll kill myself!"
He: "Whatever."

Uttered in a derisive and dismissive tone, in response to a confrontation or accusation which has been judged to be unimpressive, obnoxious, or disingenuous. Often used to dismiss someone when it is clear that rational discussion would be a waste of time and energy.

Don't tell me you believe in that "evolution" stuff! The Bible clearly states that the Earth is 6,000 years old!

Whatever, dude. Can you go bother someone else now please?

A polite and less vulgar alternative to "FUCK YOU".

Jack: "Wow, what happend to you? You look like hell today!"

Jill: "Whatever"

The most annoying thing that your girlfriend can say.

"Hey would you like to get dinner, see a movie, then perhaps go back to my place?"

"Whatever."

I don't care.

As in:
Boy: I am exhausted today. Looking forward to going home and doing nothing, hopefully you're up for the same?
Girl: Yeah, whatever.