This is a sign of complete indifference. See it's counterpart posh.
(I may be wrong but I don't care):
Bob: that's impossible.
(I don't care what the ---- you think):
Bob: that is the most idiotic thing you could do.
Me: *glare* pish.
(A random interjection saying that you don't care)
Bob: So, about the latest blah blah blah boring math blah yawn blah blah ...