Dictionary
big' deal'
Slang.
1. an important or impressive person or thing:
to make a big deal out of nothing; I hear he's a big deal on Wall Street now.
2. (used ironically as an interjection to indicate that one considers something to be unimportant or unimpressive):
So you're the mayor's cousin —big deal! Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.