Tending to "shoot off at the mouth"; opinionated, ready with a defiant verbal response. See fresh, definition #3.
I swear, that's the mouthiest kid I've ever seen - he talks back to everybody!
by house9 October 03, 2004
Oral sex performed on a male
Tyson gave me the greatest mouthy ever while I drove him to work
by Ryan M. Wilson November 17, 2007