This is an oldie I heard on a radio show playing old blues records intermingled with some old standup by AA comedians:

A horn dog was driving along and gets into a bad accident.  A few weeks later he was released but both his arms and two legs are in a cast.

He hobbled along as best he could to his favorite brothel to pick up where he last left off.  he rang the bell and the madam opened the door and saw him.  She said:

"Honey, how are you going to do anything with casts on your arms and legs?"

 He replied:  "Well, I rang the doorbell, didn't I?"