My kids are allowed to "express themselves" however they want as long as they do it sitting on their bed where we can't hear them acting like crazed monkeys. If they throw a fit, they don't get any attention, other than for me to point down the hall, and they know what they have to do. It's a lot more peaceful around here, and I am able to deal with it much more rationally after everyone's calmed down. I think it's good practice for learning how to get along with friends and, later, coworkers: no one wants to be around you when you're like this, so take it somewhere else. If they did this at someone else's house, I would take them to a room away from everyone else and tell them to come back when they're calm.
I think that if you're having to put up with obnoxious behavior like this, you have the right to make the parents uncomfortable about it, too; you really don't have to just sit there and take it.