Hold Space (or press and hold on the game) to sit; let go to stand. Sit on a plain bench: +1
Sit on anything else — broken benches, bins, hydrants, cones, fountains, BBQ smokers, US postal boxes, shopping carts, parking meters, tires, cacti, and the rare banana peel: −3
Let a bench go by without sitting: lose a heart. Three hearts and you're out.