The ability to resist any minor sickness / cold after an extended time living in a frat house. The frat house basically serves as an innoculation for various diseases. The innoculation period usually lasts 3 months upon entry to the frat house, where you will generally feel like crap, be sick all the time etc... but afterwards you will have earned your fratolerance.
My girlfriend totally caught the flu today, luckily my fratolerance prevented me from catching it when we hooked up last night.
by MCc. December 10, 2006