A girl was a prostitute, but she didn't want her grandma to know.
One day,  the police raided a whole group of prostitutes at a sex
party in a hotel and the girl was among them. The police took them
outside and had all the prostitutes line up along the driveway when
suddenly, the girl's grandma came by and saw her granddaughter.

Grandma asked,"Why are you standing in line here, dear?" Not
willing to let her grandmother know the truth, the girl told her grand
mother that the policemen were there passing out free oranges
and she was just lining up for some.

"Why, that's awfully nice of them. I think I'll get some for myself,"
and she proceeded to the back of the line.

A policeman was going down the line asking for information from
all of the prostitutes. When he got to Grandma, he was bewildered
and explained, "Wow, still going at it at your age? How do you do it?"

Grandma replied, "Oh, it's easy, dear. I just take my dentures out,
pull the skin back and suck them dry."