The only thing I've thrown is a banana peel, and that is questionable. I've done it once in a race, and probably should have just gone back to the car and handed it to them. It was right in front of the follow car though, and I didn't get a warning... but it might be different depending on who's driving. Throwing litter or bottles is a DQ offense in OBRA land.
Euro pros are a bit different. They have a whole caravan following the race, cleaning things up. And all the bottles get schlepped up by fans anyway.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter