Hill Valley Clock Tower

During the act of "doggy style" you increase your thrust speed (to simulate getting up to 88 mph) and right before you climax you scream "1.21 Giggawatts" and promptly discharge a taser to your buttocks, thus transferring the electrical current to your partner, sending them back to the future.

"I gave her the Hill Valley Clock Tower, since then she can't think fourth dimensionally."
"Great Scott!"
"I know, this is heavy!"