Based on the context and the answer, generate a question. 

Context: Another slap hit his face ( this time the opposite cheek to avoid bruising ) and he let out a choked sob . " I said do n't fucking talk to me like that . " Riku growled threateningly , shoving his fingers in and out of him faster . He took care in not hitting his prostate because he knew deep down Yura was enjoying every fucking minute of it .

Answer:

A man 's butt



Where are the fingers sliding in and out of ?