This is terrible and brilliant at the same time.

My little sister would flip her shit.

Maybe do that without polluting? Also, why without a word? Explain the mechanism, why the drama??

Yeah that would make a tantrum worse in my car, not to mention the littering.

that's a waste of money and candy, also it could hit another car behind you

To the people concerned about polluting; why not just unwrap the candy and throw it out the window? Because the candy is sugar, and the sugar should (hopefully) just dissolve.

Or, you could pop it in your mouth while they're watching.

How about instead of throwing away perfectly good candy, just take it and put it in a "trash bag" that then just goes towards the next trip's candy supply.

That's how you get ants...on the road.

Littering

My parents did this with my siblings and me with MnM's. Except every time there was trouble, my mum would give an MnM to my dad...
It made trips a lot less noisy and irritating, let me tell you.