Misha Collins of ‘Supernatural’ steps off a perfectly good high-rise

Misha Collins’ message to his kids on Monday? Don’t try this at home. Because Daddy kicked off his week by stepping off the top of a 17-story building and rappelling to the ground.

“I almost told my son what I was doing, but he’s getting to the age where he’s undertaking, um, dangerous enterprises,” the “Supernatural” actor said about his 4-year-old in the hour before his charitable descent began. “I didn’t want him to think, ‘Well, if Dad’s jumping off a building ...’”

Collins wound up leaving son West and 2-year-old daughter Maison Marie at home in L.A. and headed down to the Irvine Marriott solo for the 2 p.m. rappel. The kids’ nap time remained intact, he noted.

The rappel — in support of Shatterproof, a nonprofit that works to raise awareness and reduce the stigma of substance abuse and addiction — had the 40-year-old good sport experiencing “acute anxiety” before he put on a harness and hitched himself to a couple of ropes.

“It was OK until yesterday,” he said, “when I started to think, ‘It’s a 15-story building, and I’ll be climbing off the edge.’”

(Good thing he didn’t know about the other two floors, right?)

Blame the buddy who talked him into it — though Collins was also persuaded to participate by his own experiences watching friends suffer from substance abuse. One of his friends died.

“I had a lot of thoughts about that,” he said, when he agreed to do the Shatterproof Challenge in Orange County. “It was tragic to watch [his] struggle. We all felt so hopeful when he had these stretches of success.... It was all so heartbreaking.”

Often, he said, those struggling with abuse of substances both legal and illegal are ashamed to ask for help and don’t get the right support. In the case of illegal drugs, the stigma is further amplified.

“It’s something that is near and dear to most Americans. We’re all not too many degrees removed from someone who has suffered,” he said. “I want to help reduce the stigma.”

Shatterproof, which has already done rappelling events around the country, moves next to a 26-floor jaunt in Pittsburgh and then to East Rutherford, N.J., where participants will strap on their gear 21 stories up. Last Thursday, folks bounced down 24 floors of the Sheraton in downtown L.A.

“The kindness of strangers has had a profound impact on my life,” Collins explained. Like when he was a kid and poor, even homeless at times, and one year a person gave his mom $100 to buy Christmas presents when otherwise the kids would have had nothing.

That small act has stuck with him throughout his life and played a part in the establishment of Random Acts, a nonprofit which supports all sorts of giving. “I’m trying to find a way to have that ripple effect continue. It can be exponential.”

Despite Collins’ total lack of rappelling experience (such things are “not my forte,” he admitted) and his last-minute terror, the spirit of the adventure was fully in line with that personal philosophy about giving back and paying it forward in increments big and small.

“I want to make doing good fun, which is an element that’s sometimes lacking,” said the actor, who on Aug. 1 will kick off his fifth annual Gishwhes, the Greatest International Scavenger Hunt the World Has Ever Seen. It’s a weeklong event that has 15-person teams finding things, doing things, making things and more in bursts of what Collins called “pure whimsy, pure fun.”

A few world records have been set (longest chain of safety pins!), and NASA has taken the time to say “stop bugging the astronauts” when one task involved Twitter and the International Space Station.

This year, a solar-system exploration honcho from NASA will be joining in as part of William Shatner’s team, which also includes actor Tim Omundson, the “Judging Amy” actor whom “Supernatural” fans will recognize as Cain, the man behind Dean Winchester’s pesky mark.

“I like to break rules,” Collins said. “My mom always said, some rules are good and other rules are stupid and meant to be broken. Occasionally, those rules are laws. Right now I’m working on some projects of marginal legality.”

Wait, what? Does this have something to do with the hunt?

No, he said. And no, he wouldn’t say much more — except that fans should keep their eyes on Griffith Park around July 4th.

Never know who might need to make bail.

Follow Christie D’Zurilla on Twitter @theCDZ and Google+. Follow the Ministry of Gossip on Twitter @LATcelebs.