Learning with father

Overheard on the tram:

"Daddy, what's that blue light for?"

"That shows when there's an emergency."

"What's the green light for?"

"That's an ejector seat."

"Oh. Then what's that red light for?"

"When that's on you can talk to the driver and he'll tell you off for pressing that big red button on the door."

"What happens if you press it and ask him for sweeties?"

"He tells you to fuck off."