We go to a "potluck" get-together every couple of months. The host couple always tells newbees
1. Drinks are NOT part of the potluck fare, so BYO.
2. Bring at least enough to feed yourself. This doesn't mean you have to bring whole meal, but enough (chips, green bean casserole, pickled pig's feet) that you could trade a little of yours for a little of what others brought so you'd have a whole meal. Alternatively - if you want to just show up for the social stimulation and wish to not partake, feel free to come empty-handed.

Maybe you could modify that thought for your friends.

Good luck!

Pappy