noggin
A playful word for your head or brain.
Noggin is a casual, playful word for your head. When someone says “use your noggin,” they mean use your brain to think through a problem. If you bump your head on a low doorway, you might say “Ow! I hit my noggin!”
The word has a friendly, lighthearted feel to it. You wouldn't use it in formal writing, but it's perfect for everyday conversation. A parent might affectionately tap their child's head and say “What's going on in that noggin of yours?” when the child seems lost in thought. A coach might tell players to “protect your noggins” when teaching them about safety gear.
Noggin works especially well when talking about thinking or ideas. “Put your noggin to work” means start thinking hard about something. “That's a tough one for the old noggin” means something is mentally challenging. The word suggests both the physical head and the brain inside it, making it a fun way to talk about both bumps and brainpower.