Noun. A contraction of the phrases, 'Frat Boy' and 'Douche Bag.' Meant to save time by combining the two into one. Because frat boys are inevitably douche bags, 'frat boy douche bags' may simply be referred to as 'frat bags.'
John: Dude, I went to that party over at alpha phi douche the other night.
Paul: Oh yeah? How'd that go?
John: It sucked. There were like 2 girls and 45 frat bags.
A "bro", usually a complete douchebag in a fraternity such as PIKE, Fiji, and Kappa Sig. Famous for popped collars, sun glasses with strap, upside down visors, and multiple brightly colored polos from Abercrombie. A fratbag's sole purpose in life is to get freshman girls drunk in order to take advantage of them. Afterwards, the fratbag will "high-five" and "fist bump" his "bros" and brag about how much she wanted him.
"Hey Ry-guy! Wanna go ruffie some chicks?"-Chad
"Yeah DAWG! Let's go get us some!"-Ry-guy
"OMG! He is such a fratbag. Lets go get drunk!"-Freshman Girl