Similar to the play ground game, Tag, young boys of a privileged nature run round with their willys out chasing each other with the object of the game, if you are It, is to tag someone with your willy so that they are It.
Although this should be hard the school boys reach is enhanced by his semi as he is slightly aroused at being in close vicinity to other boys from privileged backgrounds.
"Yeah he probably got hit in the face too hard whilst playing ticky penis with his hunting frends"
"Fucking hell mate Get out my personal space. This isn't a game of ticky penis. You twat"