Mavis and Bill are getting married. Mavis' mother takes her aside one day. "Listen Mavis, we do like Bill, he is a lovely bloke, but he is, you know, a sailor, and well, they do do some strange things. So, my love, if he ever suggests, you know, doing it the other way round, you should refuse"

Mavis, "OK Mum, I will".

They get married, and all is going well. After a few months, though, Mavis starts to wonder, how that might be. So one night she says to Bill "Er, Bi-il, heh heh, how about we try it, you know, heh heh, the other way round?"

Bill, "Are you crazy? Do we want a whole lot of kids running around?"