When having sex (or making out) the two tap rule is a non-verbal way of communicating you are not comfortable with/don't like something your partner is doing. The two taps will let the partner know to stop, and go back to something you like.
Using the two tap rule- If you're partner puts their hands somewhere unwanted tap them twice on the shoulder so they know to move them.
The art that generally occurs at the end of intercourse, where the man ejaculates into the partner's eye, and the other in quick succession.
Also known as: Double-tapping facial.