Ooh, dear, this sounds awkward and as another entertainment-industry worker, I sympathise. There really is no lower bound to people's insanity about how cheaply they can get skilled labor, so you def gotta get an answer. I might do a mock-sympathy thing like, "We have to talk about my rate, otherwise I'm worried when I invoice you for my standard $400/day rate it'll break your bank." (Obviously you'd highball because it's an open invitation to negotiate lower.) Granted, that's awkward, but nothing can be more awkward than employers who don't know how to have a fucking conversation about what they plan to pay. I mean, I know you have a friendly connection here, but I usually assume people who waffle this much don't have their shit together and would therefore be terrible to work with.
Also, it sounds like other people associated with this have "real" jobs? They don't realize that this, like, _is_ your job. So of course they think of pay as an afterthought. A non-mustachian joke, like, "Hey, I'm not independently wealthy and I want to be able to eat on Christmas, so, seriously, how much are you paying me?" It might help to tell them that, aside from the money itself, if other industry folks find out that you've worked for a super low rate, that devalues your professional reputation.
And fer chrissakes, there's plenty of special holiday event work around. You can tell them that you're giving up really primo seasonal days to work for them.
I think Jack and KingCoin have offered good advice. If you're worried about burning bridges, the flipside of that is: how are you going to feel about your friendship if you're resentful of getting a joke of a paycheck? Your feelings matter too.
Only other thing I can think of is to make sure to handle the situation now, _before_ you're upset. Talking about the job when you can still reasonably call it off is not only going to put you in a better negotiating position but, more importantly, make it a more pleasant conversation because you'll be relaxed and the person you're talking to will respond to that rather than the fact that you're angry. I mean, you can act cheesed off if you think it will help, but it's different from being _actually_ angry.
Okay sorry when I write it out this seems super obvious verging on condescending. I'm sure you'll do fine.