Although I think the idea of nonconsensual hat drops is so fun and fantastic.
I wish I could register myself as being up for any sort of serendipity like this. While I like the idea of a hat randomly dropping onto my head, some people may not.
As a counter point, the hat is a great way to protect against AC water drips.
My biggest fear about walking around any city (but NYC in particular) is an actual AC machine dropping onto my head. Maybe you could offer the choice to drop down a hard hat on streets with high AC unit density (and then pick it up when I leave the area).
I have never liked it when the ACs drip on me in midtown let alone a hat dropping on my head!