The sexual act/assault of punching a Gilf (grandpa or grandma ) you are mounting up the ass in the back of their head, causing both their rectum to spasm and contract pleasurably around your member whilst simultaneously sending their dentures flying out of their facial orifice. See Donkey Punch
My Goth, Daefith, can yoof see wheh you sendth ma tehf??
Sorry, Ray, I must have Donkey Launch'ed them into space.