This is a joke my grandpa just told me (he was a Navy guy).
Two boys were playing in the sandbox with a girl; the boys’ names were Tom and Dick and the girl’s name was Sally.
Tom decided to challenge Sally to a contest. The rules of the contest were as follows: each child had to build up a pile of sand, sit their fannies on top of the pile, then break wind. Whoever blew the most sand off of their sand pile wins! Tom’s friend Dick would be the judge who decides that.
So both Tom and Sally build their own sand piles of equal size, they both sit on top of their sand piles, and both of them pass gas and blow off a lot of sand. Dick looks at the sand piles and goes, “Hmm…it’s hard to say who won this one. Let’s do a rematch!”
Then Tom and Sally made new sand piles of equal size and parked their fannies on top of their sand piles. Sally was able to blow almost all the sand off of her pile but Tom couldn’t pass any more gas no matter how hard he squeezed.
Dick was shocked as well, so he went over to Sally to investigate. He pulled up her skirt and removed her panties to take a look. His eyes widened, then he looked at Tom and said, “Well, no wonder, Tom! She’s double barreled!”