When a male person vigorously inserts and retracts his forefinger from his own anus, whilst with his other hand; angrily masturbates to an explosive climax.
Note - is not an exclusively solo act - one could improvise and perhaps masturbate himself while his housemaid or sister assisted with the fingering portion.
1) ...gentleman one to gentleman two "I say, I spiced up my evening tug last night, and fiddled the badge with my forefinger. I believe my son calls it a fingery bum wank".
2) ...young stud remarks "Jesus I had a shocker last night..I convinced this chick to help me out with a fingery bum wank and ended up shitting all over her hand and wrist"..... young studs friend "...nightmare, but respect!"