Oh **** me, do you have any idea what sort of concentration is necessary to get a contact high? I doubt it, based on the level of naivete you're displaying right now. You need to either have:
1) A TON of people smoking in a small area which, by the way, probably wouldn't happen in public places considering California's already uber-strict prohibition on public smoking.
OR
2) You'd need to be in a tiny, tiny room that is not well ventilated by any stretch of the imagination.
I mean seriously, ask the people who have been there: it's harder than HELL to get a contact high unless you're ****ing
trying.