A dumb ass is someone who does or says something retarded.Sometimes people are dumb asses and do stupid shit.
Larry your a dumb ass you put your dick in the toaster.
any thing Joe Biden says or does shows how big of a dumb ass he is
dumbass: the dumbest dumb ass in urban dictionary is the dude who went to the google store to get an extension for his penis.
"hey , did you hear about the dumb ass who went to the chrome store to get an extension"
"Yeah he sure was a stupid dumb ass short dick mofo"
you.
dumb-ass: OH ye! let me just go search my name up on URBAN DICK