butt wanker 

A person who inserts their finger/fingers or some object into their anus while masturbating.

That guy is such a butt wanker.

butt wanker by MITB April 19, 2006

buttwinker 

When there is a wiener on your butt also known as your anal hole and the male misses your butthole by trying to insert it in your butt.

OMG hes totally a buttwinker , he missed so bad

buttwinker by Madisyon banks February 19, 2017