"Sex" isn't speech. Period.
So if I draw a picture of two imaginary people having sex, who is having sex, really? Where's the sex in that case?
I believe the Founding Fathers had something a little different in mind than sexual "intercourse" or "oral" sex.
Probably. They probably didn't envision "Car and Driver" either, but that's the nice thing about the universal principles they laid out for us - we can apply them to things they couldn't possibly imagine or predict.