The nagging feeling that, no matter what, you're getting screwed over by the car rental company.
Eddy: There! I used my Air Miles, so instead of this car rental costing me $350, I'll only have to pay the tax.
Car rental gal: Okay, with the additional driver, booster sear, and taxes, that'll be... $351.
Eddy: I got a bad feeling about this... must be the rentanoia.