Someone who’s rhythm is so bad they can’t achieve orgasm by manual masturbation. Once they start they can’t stop, and just can’t quite get to completion. Producing a dysrhythmic fapping that can be heard for hours, until chaffing causes cessation.
Bob was diagnosed with Dysrhythic Masturbatory Syndrome (DMS), his neighbours had filed noise complaints for odd and annoying clapping sounds at all hours of the day and night.