Scene: Grandma's Family Birthday Dinner, with the fam at Grandma and Grandad's.
Bear: Did you know that only ducks quack?
Adult (possibly Grandma): Ducks?
Bear: Yes, only Ducks (the females) quack and (Mallards) don't.
Wombat: And mushrooms do nothing!
Everyone (except for Wee Grandma aka Great Grandma who doesn't get it) instantly devolves into uncontrollable hysterics.
There weren't even any mushrooms in the dinner either - in case you were wondering.