To masturbate, by not actually consciously moving your hand.
The best option is to wait for an earthquake (Though this may be a rare occurrence in some parts of the world not along a fault line) but that is what makes the situation even more romantic when the time eventually comes (pun).
Follow these steps:
Step 1 - Hold genitalia tightly in hand (Not too tight).
Step 2 - Wait for earthquake (Warning: May take time).