I have come across non-sexual cockslapping. (Umh, I'm not sure if some exhibitionism was involved. It sounds very likely afterwards..)
When I was in military service some recruits used cockslapping in order to show their dislike of other persons or to punish for stupidity. A cock was slapped on the back of stupid person or preferably on the cheek. (However, the latter is more difficult because you have to approach a moron unnoticed -- otherwise he will dodge.)