This joke is dated, but it's still as fresh as a daisy. So to speak.
Dolly Parton and Princess Diana die simultaneously, ascend into the clouds and are made to wait in line with the others outside St. Peter's Gate. They both know they have to impress him to get through the gates. Only one of them can get through though, so they pull out all the stops and show their best assets.
Dolly lifts her gown and shows her magnificent breasts, thinking, "I'm a shoo-in! Hands down!" Princess Di then steps forward lifts her gown and begins douching. St. Peter points to Princess Di and beckons her to enter through the gates. Dolly, surprised and angry, cries out, "Are you serious? I show you this great pair and you let HER through?"
St. Peter replies, "Sorry, Dolly, but you know a royal flush beats a great pair every time."