The mutual passing of fecal matter from one person to another, through a passionate kiss.
Let's start mud balling till we puke!
by mud ball November 16, 2007
And upgraded form of tea bagging. This is done by covering one's own testicles in fecal matter before placing them against the face of the victim.
"You goin' to let him get away with mud balling you?!"
by Mistearea April 26, 2013