Riddle

What activity uses all parts of the body, lasts two hours or more, requires many positions, involves heavy panting, where the ultimate goal is to stick one thing in another over, and over, and over again, cuz it feels so darn good, and afterwards you're all smiles drenched in sweat and you can't wait for it to happen again next weekend?

Nerves

Some people really, really, really get on my nerves.