Hot for the Teacher?

At age 26 that I'm near the same age as some of my potential professors. Some of which who will be (male or female) attractive, interesting, and someone that I'd like to get to know better outside of class. These in some ways are my peers, but only not.

I've never really thought about that before now. I never thought it would be an issue, because it didn't really occur to me until this past birthday that 'I'm one of the grownups now'.

There are lines that cannot be crossed even on the level of just being friends with a Professor while still in their class. That is a given.

When though is it appropriate to have outside social contact? When your out of that class or when you've graduated?

What are the rules of this sort of thing when you hit grad-school?

In conclusion, I admit nothing.