"Billy-Bob and Billy-Joe" joke

It's 10:00 at the police station. The only officers working that night are Billy-Bob and Billy-Joe. And the power goes out and stays out all night. But this doesn't bother them.
Billy-Bob: Billy-Joe can I stick my finger in you'r belly-button?
Billy-Joe: Sure Billy-Bob.
A few hours later...
Billy-Bob: Billy-Joe can I stick my finger in you'r belly-button?
Billy-Joe: Sure Billy-Bob.
It's midnight...
Billy-Bob: Billy-Joe can I stick my finger in you'r belly-button?
Billy-Joe: Sure Billy-Bob.
Billy-Joe: Billy-Bob that's not my belly-button...
Billy-Bob: I know... and that's not my finger.