I didn't have time as the lights were about to change so I shouted "You dropped something mate" through his open window. He said something I couldn't make out as he overtook me.
Urgh - pet hate of mine. Told someone off for dropping litter in a park once and they complained about me having a go at him in front of his kids. Yeah - I'm the one being a bad example to them.
Pick it and hand it back telling them they dropped s0mething