Accidentally play the violin

Going to the bathroom for an innocent reason (bathing, hygiene, grooming) but ending up masturbating furiously or partaking in other sexual acts often that are intense whilst in the bathroom. A verb describing hormonal boys but is not exclusive to the gender.

He went to go pee but you could hear him accidentally playing the violin.
Billy used to frequently accidentally play the violin but now he mostly does it in public.
"I'm going to the bathroom now." "OK but be careful to not to accidentally play the violin"