Having sexual intercourse without a condom.
Joey tried to frat dog Kayla, but she told him to bag it.
by Dan Teeman March 01, 2008
A person who enbodies all that is being fratty. Sometimes used to mock those in fraternities. Mainly used in a joking manner to describe living a life of partying.
I consider myself the biggest frat dog on campus unlike those non greek herbs.
by JaKy April 26, 2007