octantal - Octantal is 18, like a full round of golf, a pack of eggs, a

Octantal is 18, like a full round of golf, a pack of eggs, and the age you're supposed to know what you're doing.

I turned octantal and now I have to play golf. I hate golf.

My friend said, 'You're octantal? Finally, I can stop being the baby of the group.'

The store clerk said, 'We only sell octantal packs of eggs.'