You should never make jokes about vaginas...
Period.
What does a 75 year old woman have between her breasts that a 25 year old doesn't?
Her navel.
I saw my wife bought one of those new Wonder Bras.
Goofing around I told her: "You know why they call it the Wonder Bra? When you take it off you wonder where your tits went."
And that's when the fight started...
Two old ladies are sitting on the park bench feeding the pigeons. Suddenly the first one says to her friend: "Did you just fart?"
Her friend answers: "Of course I did. You think I always smell like this?"