It hurts to laugh.

If you’ve ever watched Jackass — and, apparently, people do — you’ll get the character of Doug in Rajiv Joseph’s Gruesome Playground Injuries. Rob Maass plays Doug, opposite Tess Cinpinski’s Kayleen, in the intense Youngblood Theatre staging that opened Friday evening.

Maass throws himself into the role of self-destructive, daredevil bad boy with the same abandon Doug shows in bicycling off the church roof for a thrill or, in despair over Kayleen’s rejection, staring down fireworks at close range. (You really can put an eye out with those things.)

Cinpinski’s Kayleen shreds herself, too, but without Doug’s Evel Knievel bravado and relish. She cuts herself and vomits in private shame, which she shares only with Doug. She is his female negative image.

The play is two things at once: A gritty drama about lower-middle class types too damaged to take any joy in their obvious love for each other; and a tour-de-force theatrical contrivance. The suffering of these sad people and the tenderness they occasionally lavish on their partners break your heart. And yet Joseph takes their calamities so far over the top — I mean, the guy gets struck by lightning — that very funny black comedy breaks out with surprising frequency. Nothing lances a wound like comic irony, but the emotions here are very complex. You can’t help laughing, but you feel a little guilty about it. Interesting.

Joseph structured the play in eight episodes. The characters meet in the school nurse’s room at age eight, and we see them last at age 38. In between, the episodes jump about in time — 21, 31, junior high, mid-20s, and so on — so you have to assemble the big picture from snapshots.

On opening night, Cinpinski and Maass (both 26) worked just a little too hard to sell us on being children. The scale of the acting there was, say, Pabst Theatre; less would have been more in the very intimate black box on the fifth floor of UWM Kenilworth Building. Even so, the episode was a very near miss.

The two actors, directed by Benjamin James Wilson, hit the bull’s eye in the other seven scenes. They commit fearlessly to characters battered by only partly accidental and entirely self-inflicted violence. They establish age and damage level instantly and casually in all seven of these scenes. And they interact so frankly and thoroughly that you feel like a voyeur. You can almost feel Cinpinski’s Kayleen tearing herself apart in a scene in which Doug is in a coma. She’s angry at his recklessness, guilty at her anger, ready to laugh at the black humor of it all, and guilty about that, too. Cinpinski registered each nuance in one-to-one proportion to reality. She was all Kayleen and no Tess. Great acting, there.

Again, though, this play and this staging both arrest us with the true human moment and charm us with theatrical contrivance. At the end of that coma scene, Maass and Cinpinski broke and calmly changed clothes in full view. As Maass donned new wounds for every scene, the suspense built: Oh my god — now what?

Gruesome Playground Injuries runs at 8 p.m. Fridays and Saturdays through Aug. 27 at UWM’s Kenilworth Studio Theater, 1925 E. Kenilworth Place. A pay-what-you-can show is set for 7:30 p.m. Monday, Aug. 22. Tickets are $15, online or at the door.

The Youngblood crew — gluttons for punishment, apparently — is also running an outdoor show, Minnesota Moon, at Trimborn Farm Park. Admission is free, but you have to attend Playground Injuries or sign up for the company’s mailing list to get a ticket.