Similar to dry humping, wet humping occurs when two partners engage in grinding without insertion in the shower, hence WET humping. The penis may turn red the next day if wet humping persists for more than 15 minutes.
My dick hurts from all of that wet humping last night.
She wouldn't have sex with me, but we were wet humping for 45 minutes. This is the worst of all possible scenarios, because now I have been exposed to whatever venereal diseases she carries without being able to get credit for fucking her.