Someone who tries too hard to be cool. (flips up their collar, wears sweatbands without playing sports) The phrase comes from the fact that they probably don't get a lot of girls, so every party they go to would be a sausage fest and, therein lies the word's origin. Originally started by a bunch of guys who just made up the word.
dude1"That guy's totally sauce."
dude2"what, on steroids?"
dude1"no, that's the definition below this one"