I'll be going to a potluck dinner next week with my dance peeps. The hostess, our instructor, has asked us to bring something that doesn't need heating. Also, we'll be dancing beforehand for 2hrs so the food will be in the car, in a cooler bag, for about 2.5-3 hrs. The forecast says it'll be 20C/ 70F (I don't believe it but that's what it says). What would be a good thing to bring?