Heavy Petting
I'm not sure if this phrase is used anymore. I think it has been replaced with the more open ended Fooling Around. What I don't quite understand is what is exactly being pet during a session of heavy petting. Well, that's not true either. But I guess what I'm trying to say is that I wouldn't choose to describe the act as petting at all. Heavy Fondling may be a more appropriate phrase, but it sounds too perverted. Strom Thurmond was a practitioner of fondling and I don't think anyone would want to associate their acts with the dearly departed Strom. Heavy Massaging perhaps? Nah, that sounds too clinical and orthopedic.

Now I know why everyone says Fooling Around.