Top Definition
A phrase that has been shortened to two syllables, meaning shut the fuck up mainly used to annoy friends by saying it non-stop whenever they try to talk.
Amanda: Hey, guess what I did today, I went -
Alex: shuddafuckup.
Amanda: you shuddafuck up!
Alex: shuddafuckup.
Amanda: you shuddafuck up!
by Amanda Is Cool
January 18, 2009
