But OCD isn't always -- or just -- about germs. It can be any thought that makes you anxious and won't go away.
"Checking things, is the doors locked, is the water running," said Grayson. "We have people who have a nasty form of perfectionism, students who want to do their work perfectly."
That could be a good thing -- "except that you have a paper that you never finish because it's not perfect," said Grayson. "There are a lot of obsessions that are primarily mental, meaning they don't have something happening in the environment."
Grayson's virtual camping trip through the hotel is based a shortened version of an actual camping trip he leads, on which OCD campers experience a therapy he calls exposure.
"Exposure is all about what are you afraid of, let's have you come into contact with it," Grayson said. "...You can decide that you would like to live with uncertainty and what choice do you have. The saddest thing about all the rituals you do: You never get the prize. That you are in just as much danger either way."
The tire-kicking addresses a fear of impulsively doing harm. The time spend playing with knives is for people with a fear of becoming homicidal, to prove to themselves they won't hurt anyone with a sharp object.
For Lange, the big challenge would be the outdoor part of the excursion -- just imagine the germs.
Then Grayson came up with a shocker.
"Is there anyone here with contamination issues who is holding a bottle of Purell? I'm just going to ask, can I have your bottles of Purrell?"
There was a lot of hesitation in the room.
"You don't have to do this , but you don't have to get better either," said Grayson.
Lange handed over the hand sanitizer.
"The doctor just took away my hand sanitizer," she said. "I'm feeling really nervous about that, because now I like have no safety net. ... I have to venture out now and I don't have any kind of backup for my OCD. It's scary."
Grayson explained the exercise.
"Your goal is, you're now going to live in a dirty world that is dirty all the time. You will never be fully clean again. Now, the good news is, you never were fully clean. ... The most torturous part of OCD isn't so much the exposure that happens in real life, it's trying to fix it. So you know, I can get dirty in 10 seconds, but that might take me 10 hours to fix."
It was an odd sort of Odyssey, this group of people with OCD trekking around downtown Minneapolis confronting their fears.
"So my question is, how do you guys feel about dumpsters?" said Grayson. "Now, people think what we do is a tad odd, and what I want to point out is that, in a sense, everything we do is normal. People regularly do put trash in a dumpster, and then they just drive to work, and they may even eat at work without washing their hands."
Lange said being with the group made it easier for her to step forward and touch the dumpster. But it still took quite a pep talk from Grayson to get her to do it.
"Think about how much it has stolen from you, how many times you've been humiliated because of your OCD," said the doctor. "How many times there's something you wanted to go to and you didn't get to go, how many times you wanted to be in a relationship and your OCD stood in the way. And if you have parents or loved ones, how many times you tortured them, you made them do your rituals. You're beginning to try and take your life back."
Lange described the experience afterward.