If they are good friends, I'll give them a roll of wonder under and show them how to use it.
I they are neighbors, co-workers or people I want to remain friendly with, I'll give them a coupon and tell them what to buy.
If they are annoying people I tell them about it and where they can get it for them selves. Or i just look at them blankly and say something like, "hem? what's a hem? People do that? Reallly?"