Mom, I need $400 for a fin. None of the other robots have antennas anymore. They all have fins.
They have what?
Honey, that's a lot of money.
YOU NEVER LET ME DO ANYTHING! I HATE YOU!
I can't talk sense to my parents. I laid out my case, but they are idiots. They have no sense of reason or logic.
On to Plan B...
Shoplift a fin from the mall and smuggle it to school in my backpack... Also, get a tattoo on my face and pierce my crotch. Then they'll wish they'd bought me a fin.