The antonym of Talkin' Trash. The belittling of one's abilities or achivements, especially in a competitive setting, going beyond being humble.
A: You're gramps could probably beat me in an arm wrestling match.
B: C'mmon dude, you just beat the strongest guy in gym class.
A: I just got lucky there...
B: Quit, talkin' brand new goods and lets do this!
(A smokes B in said arm wrestling match)