For team stuff... I always bring enough for siblings. I consider them cheerleaders. I don't know how I'm always first up on the snack roster (seriously, always)... but everyone else tends to follow suit.
For other stuff... just ask my son. No means no. I can say no 10,000 times with a smile on my face. (It drives him insane. Esp when he's spoiling for a fight). The other kids who are around me GET THAT after a couple times, but they're reeeeeeally baffled by it in the beginning. What? I aks you 50 times and the answer is STILL NO??? What gives? My son says it's not fair. With HIM, if he asks receptively, I start taking away stuff! Ditto, I'm willing to bargain... DOWNWARDS.
"But I want 5!!!"
"1 or 0."
"3?"
"0 it is!"
"No! Wait! 1 would be AWESOME! PLease, please, please.... just 1???"
Sometimes (if he's pitched a fit about more), he gets 0. "Next time, be happy with what you've got. Nothing ventured, nothing gained, in asking for more... but if told no... you'd better be grateful for what you DO have!"
I'll pull this with OPK's when were out and about, as well. I'm ALWAYS willing to negotiate downward :) :) :)
Trick o Treating, etc... I just wink at them. Good effort, no dice.
Kids amuse me. If they've gone past amusing into irritating, they've just achieved a major accomplishment and are in some very less than distinguished company.