Yep, we had a few geeks on the football team, no one was bothered.

I think the governing principle is that people want to belong to a social group, and to achieve that belonging, they need to be as un-like other social groups as possible, to make their affiliation clear.

In other words, cool kids are fine with hanging out with un-cool kids, if it can be done in a way that does not involve un-coolness at all, so they don't become un-cool by association.