I have an overall pet peeve with the phrase "So what?". I feel as though when you are having a discussion or argument or what have you with a person and they get to the point of saying "so what?" they might as well be saying "You have hit a brick wall because even though I no longer have a valid argument I am also not in the slightest bit prepared to give in on my opinion the slightest bit."
Example from a long time ago:
Me: Why'd you buy a bike and then put it in storage?
Her: Because it doesn't work and I don't have the $$ to fix it up yet.
Me: But didn't he (her partner) want to get a bike too?
Her: Yeah, and he will but he'll just have to wait because we don't have the cash right now.
Me: But he was the one who actually *wanted* a bike and was gonna take it to ride across country.
Her: Yeah, but I found this one and I wanted it and the auction was ending.
Me: But it doesn't even run, and you're not getting it fixed up AND because of your buying it he's gonna have to wait that much longer to get his which was why the bike buying expedition began in the first place!
Her: So what?
ARGH! It's the equivalent of stamping your foot when you're not getting your way in my opinion.
Okay, end vent.