Yeah, I know what you mean. I sometimes use "hook up" to mean the first option, but it someone says it to me, I assume they mean "got naked and enjoyed themselves."

The conversation was not all that in-depth, but it was something like us talking about people using hook up to mean sex versus to mean everything-but-sex and then wondering whether it was regional. So I was like, I should make an LJ poll. And then this happened.