2) When people over 35 come in to your restaurant, seat them directly under the speaker playing really loud middle eastern style vocals mixed with thumping bass. If Old People are going to come to Hip place with Sexy Tattooed Staff and busboys with liberty spike mohawks, they should suffer for daring to dine with the elite and hip. Note that the -other- table of Old People seated next to the speaker didn't complain; they are thankful to even be here, as they are at least 45!
3) When the people over 35 politely ask for another table so that they can talk to each other and hear, act really put out. Move them to a dirty window table; wipe it down half-heartedly. Make sure that no one brings them water or asks if they want drinks (despite not being very busy) for at least 20 minutes after they are seated, since these are obviously Difficult Customers.
4) When the waitress finally arrives, have her act really surly and angry, as if these customers are the cause of all her woes, if not all the problems of the world. Besides, when you are thin and punk and have a lip ring, you don't have to be good at your job; Old People should be glad that you'll even bother to talk to them, much less bring them food.
5) When an Old Person says there's a problem with her order, as it has cheese on it and wasn't described that way on the menu and the Old Person isn't fond of cheese, DON'T say "Oh, I'm sorry, we'll fix that for you". Rather, exhale loudly, and say with a begrudging sigh, "I'll go talk to the kitchen". Sulk off.
6) Don't have the kitchen remake the order; rather, scrape the cheese off and put some more sauce on the food. Don't even change the lettuce garnish that's got shredded cheese hidden in its folds.
7) Keep customers waiting for their check. The more time they get to spend in your restaurant listening to whatever Green Day ripoff you are now playing over the PA, the better for their musical education. They are probably stupid about music anyway, since they are Old; whereas you were 11 when Grunge happened and therefore know something about good music.
8) Wonder why the waitress got a $2 tip on $17 bill. Not that the waitress would know this, but if one of the Old People hadn't been a waitress at a 24 hour restaurant one summer, and the other Old Person hadn't once co-owned a restaurant, the tip would have been half that. Wonder why forgetful and/or cheap customers leave nothing; but pissed off customers leave something small enough so you know they didn't forget to tip.
9) Go back to gossiping, smoking, or doing whatever it is that the customers were interrupting when they had the audacity to walk in and want food.