Have seen it twice in my career...
The first time I saw it the defender touched the ball after reaching through the throw-in plane and one of my partner's whacked him. The coach complained that the offensive player "baited" his player into the infraction. I replied, "well it worked."....
The second time this happened, the offensive player screwed up and held the ball on the inbounds side of the throw-in plane where the defender stole the ball and dunked it. Had to settle a coach down on that one as well.
There's also the possibility of having a held ball if the thrower holds the ball across the throw-in plane and the defender ties him up.