The act of walking around a night club or other social setting and scanning the room for the opposite sex to approach and begin seducing. This behavior is very obvious to others and the body language of the subject looks like that of a wildpredator looking around for a viable prey.
That horny old man who is staring at those pre-teens ain't fooling anyone - he's preding.
When someone spends too much time in a shower, bath or swimming pool and ends up with soft, wrinkled skin. This then leads to the person looking like a Prune, hence the term.