Two of my kids were playing Lego, and my youngest was losing ground in some sort of battle. At last, he played the "my character has an unbreakable weapon" card. The older one, sensing victory was near, said "oh yeah, well if it's invincible, what's it made of?", so my youngest, creative as ever, instantly replied with the two toughest things he could think of: "It's made of Hammers and Sharks". There's no way I was going to pass up the opportunity to use that.