How to play Firetruck Game

One day, a lovely couple decided to play a random game while waiting for their food delivery.

BOY: Let's play the firetruck game.

GIRL: How do we play?

BOY: I run my fingers up your leg, and you say "red light" when you want me to stop.

GIRL: Okay.


Few seconds later...

GIRL: Red light! Red light!!!

BOY: Sorry, Firetrucks don't stop on red lights!