There’s this thing about cheap jokes: They can either be just cheap jokes, or they can be incredibly funny cheap jokes.

And it’s the incredibly funny kind that fill the two-plus hours of "Shear Madness," what may well be the longest running non-musical play in history. It’s been running in Boston for over 30 years and shows no signs of slowing down.

The Milwaukee version, with our very own John McGivern at the helm, is running at the Northern Lights Theater at the Potawatomi Hotel & Casino. It’s been here before, and if I’m any judge of popularity, it will be here again.

The story is set in a hair salon, which, as designed by Rick Rasmussen, is absolutely spectacular. And while the space is built more for music than theater, it works very well in the confines.

The secret to this play is that it is interactive with the audience. But like any murder mystery – and that’s what this is – it only works with actors who have the chops to pull off a script that is dotted with local and timely references and jokes, and calls for actors who can play along without a script. This cast is so comfortable with this thing that it’s easy to forget you’re watching a play; you might think this is a real life situation, albeit a very funny one.

McGivern plays Tony Whitcomb, the flamboyant and girlish salon owner. Mary MacDonald Kerr, who may well be one of the most versatile actors in Milwaukee, is Barbara De Marco, the gum-chewing, boob-bouncing, very experienced partner of Whitcomb.

Jenny Wanasek plays Mrs. Shubert, the aging and wealthy patron of both the arts and apparently some young man with whom she has just spent a delightful afternoon. Norman Moses has moved seamlessly from his turn at the Illinois Shakespeare Festival this summer, becoming Eddie Lawrence, who is there for a haircut and perhaps even more.

And finally there are two cops, led by Nick O’Brien – played by Patrick Noonan, who has done this part enough that he has a freedom to lead the audience through its paces with nary a misstep. He’s joined by newcomer Matthew Huebsch who plays his partner with the kind of naivete that you’d expect from a junior cop.

I am not going to come even close to revealing the murder, the investigation, the outcome or anything else that has to be part of the audience experience. Let’s just say that it’s easy to get wrapped up in the story, while taking plenty of time to laugh.

There is not much subtle about this humor. It’s really a bunch of cheap jokes delivered with warmth and skill so that it’s easy to laugh even through the groans. Some of it is spectacularly funny.

Part of the charm of "Madness" is the ability to dot the script with so many local references that you’d think the thing was written in your hometown. I can’t even come close, but on the list are Downer Avenue, Water Street, Cudahy, The Shorewood Players, Mike McCarthy, Lake Drive (both south and north), the Milwaukee Brewers, Ryan Braun, David Gruber and on and on and on.

McGivern is a masterful comic actor, and his mincing around the salon and his flights of emotional fancy keep everyone off balance. He can do more with a sideways glance than almost anyone can do with a page full of dialogue.

Kerr has just about the best comic timing you’ll ever see on a stage. And with her long black hair and her cleavage down to there, she plays the tart we all either knew or wanted to know.

Moses is the likeable everyman, but it’s clear that there is something else going on underneath that boyish charm. He’s got the kind of skill that make actors glad to be actors.

And Wanasek is a marvel. I think the last time I saw her she was playing Emily Dickinson at Renaissance Theaterworks. In this thing, she has some of the funniest lines of all.

She is hidden in a workroom while the investigation proceeds, but each time the door opens she kicks in with a line. First it’s "I am going to stand on my constipational rights." The next time the door opens, we hear her say "They had to call it PMS because Mad Cow Disease was already taken."

Writing down the humor from this play is an exercise in futility, so I’ll stop. But I will say that when you go see this, you’ll remember more jokes and funny lines than anybody really has a right to.