Why don't we do it in the road?

So I trundle into the riverside rest area. The river is high and noisy. A motorbike is parked up under the trees. I fire the rubbish onto the truck, and have a wander about with my litter spear. On the wooden steps down to the river are a couple going hard at it. They don't see me. I slide back to the truck, and quietly drive away. Spring is truly here.

Lennon/McCartney
Why don't we do it in the road?
No one will be watching us
Why don't we do it in the road?