Integer System:
1. Hand holding and/or sideways snuggling.
2. Kissing.
3. Snuggling proper.
4. Boobage.
5. Dry humping.
6. Handjobs.
7. Fellatio.
8. Cunnilingus.
9. Sodomy.
10. Coitus.
11. Goats.
-1. Autofellatio.

Irrational System:
pi/pi. Eye contact.
e/e. Talking. (Slightly >pi/pi.)
e/2. Holding hands.