Your 10yo brother is/was my kind of guy! lol
We have a whole group of sayings like that in my family. My youngest sister was really fond of rhumba panties, which she wore once she was toilet trained. She called them "ballet panties."
A few months after she was permanently wearing those panties, my dad asked her to clean up the toys she had dragged out. Her answer? "I don't have to, I hve ballet panties on!" Hahaha!
Now, when anyone in my family wants to NOT do something, they say: "Sorry....I have ballet panties on."