A frat mama is a sorority girl who takes care of you like a suga mama. Also classified as a sorority gutta bitch. It can be your sorority sister or your bitch that makes you your sandwiches if your a frat boy. Typically, frat daddys have frat mamas. In some cases frat mamas sleep with frat daddys and do their laundry, dishes, and dirty work for popularity among a certain fraternity. Or in other cases, a frat mama is a sorority sister whom you have a special bond with and you do each others dirty work like washing each others clothes, dishes, going shopping together, wiping each others asses etc etc.
fratty fatty #1: Dude, Craigs the biggest frat daddy on campus. He gets more frat mamas to do his dirty shit than the entire fraternity combined.
fratty fatty #2: Yeah, you should see his frat mama of the week, she even scrubbed the nasty shit clean off his feet. It looked like he was growing third foot from all the frat nasty calluses on his heels.