Animaterra: I heard it this way:

Q. Why is it Baptists don't believe in having sex standing up?

A. Because it might lead to dancing.

It's not only Baptists of course. My wife grew up in a very small town in southeastern Minnesota that only had one church, and that was Lutheran. The local high school didn't have dances because the Lutherans opposed it. I think this was an old Norwegian or Swedish viewpoint. It has changed since then. Anyway, other kinds of Lutherans are not so stodgy.