stfugenius 

The kind of smart, know it all, that just wont shut up. Often just pretending to know things, though a real stfugenius wont take so long to shut up.

John is such a stfugenius, he just keeps going on about rocket physics, i dont even care anymore!

stfugenius by Alex Goold June 18, 2007

[stugenius] 

Someone who is supposed to be smart but has no common sense. Or stupid genius.

Guy A: Dude, you know Tony from the Chess club? He was jaywalking and got hit by a car.

Guy B: Man, that guy's a stugenius.

[stugenius] by Rand0mV1rus December 18, 2008