Gathering socially is one of my favorite things to do. I like socializing even more when it includes food and drink. Something that seems to be ever present at most gatherings however, is polystyrene ware. The stuff is great at keeping food at temperature and is liquid-proof, but it's also lethal to some wildlife and permanent in the environment.
When I was a child I would go down to the ocean shore to watch the fishermen (yes, they were all men) work their poles. They had two or more each. Along with those, their gear included a tackle box and a polystyrene bucket to hold their catch. The irony here is that polystyrene balls (you know, when you look close it is made up of bunches of little balls stuck together) that are loosed are often ingested by fish. The balls do not degrade and remain in the fish bellies, fooling the fish into thinking they are not hungry, then the fish starve to death.
I will not list the pros and cons of polystyrene, nor will I compare it to other products that are used for the same purpose here. What I will do is simply say that, using common sense, I find the use of anything throw-away is going to be worse on the environment than using something you wash. More work, but much less guilt. So, I try to make it simple for everyone; I carry my own coffee mug in my car. I can drink from it and eat from it, and when I am done, I can take it home to wash.