The advice I gave a different reader about dealing with a guest horning in on the action at an orgy applies in your case: “Even kind and decent people can be terrible about taking hints—especially when doing so means getting cut out of a drunken fuckfest. So don’t hint, tell. There’s no rule of etiquette that can paper over the discomfort and awkwardness of that moment, so you’ll just have to power through it.”
Swap out “drunken fuckfest” for “drenchin’ piss scene,” and the advice works—up to a point, PEE, because the person in your case who needs telling, not hinting, isn’t one of the guests, he’s the host. (And he sounds like a gracious host. I mean, drinks, towels, and canapés* at a piss party? Swank.) But your host’s behavior sounds genuinely annoying. Hosting a sex party doesn’t give someone the right to insert himself into someone else’s scene, and stupid jokes have the power to kill the mood and murder the boners.
So what do you do?
Well, you could send your host an e-mail or give him a call. Thank him for the invite, let him know you appreciate the effort he goes to (such delicious canapés!), and then tell him why some people say they’re coming and don’t show: You’re too loud, your music is awful, you have a bad habit of horning in on the action, and you need to learn some new jokes to tell when you’re pissing on someone (or, better yet, not tell any jokes at all). But I don’t think ticking off a list of his shortcomings is going to get you anywhere other than crossed off the invite list to future parties.
So why not make your own piss party? You don’t need a big backyard—I mean, presumably your place has a tub. Supplement your tub with a couple of kiddie pools on top of some plastic tarp laid down on the living room or basement floor. Ask your guests to keep it in the tub, pool, or on the tarp. You get to choose the guys, you get to select the music, and, as host, you can lay down the law about making jokes and horning in on the action: Both are forbidden, and joke-telling horner-inners will be asked to pull up their pants and leave.
One last thought: If you have it in you to invest some time in getting to know this guy—if you treat him like a human being—you might be able to draw him out on something that clearly frustrates him: guys who say they’re coming to the party but don’t show. If he seems genuinely baffled, PEE, that’s your opening to ask if he’d like some constructive feedback. If he says yes, you can very gently run through your list of ways to improve his parties: no jokes, better music, and a “no horning in” rule for all (not just for him).
* Yes, I know: There were canopies at the party, not canapés—tents, not hors d’oeuvres. But I read it as canapés at first, and the mental image of piss players daintily eating canapés between scenes was so much more entertaining than the mental image of piss players huddling under canopies that I stuck with my original reading.