For two years now, passengers boarding the newly-built Jerusalem light rail on the second Sunday in January have been in for an unusual surprise: the sight of their fellow passengers nonchalantly taking off their pants and riding around in their underwear.

Some 50 people dropped trow on the Jerusalem train Monday evening, double the number who participated in the event last year, organizer Boaz Balachsan, a Jerusalem-based artist, said.

“It was lots of fun,” he told The Times of Israel. “And not just for the 50-odd participants: in a city known for its sheltered, conservative communities, many light rail passengers responded positively to their pantless co-passengers’ antics.”

“The reactions were wonderful,” Balachsan said. “With the exception of one probably unstable woman who was yelling at one of the girls, people reacted very well. People laughed, asked us what we were doing.”

The pantless passengers thought up creative, tongue-in-cheek explanations for their unique dress code.

“One guy claimed he’d forgotten his pants, another said he was raising awareness for butt cancer,” Balachsan said, laughing. “I was even told that one guy heard two girls talking amongst themselves and guessing that it was a protest over rising clothing prices.”

Ultimately, he said, the pantless ride was a bit of fun in a city that “really needs it.”

No Pants Day harks back to 1986, when a New York City resident accidentally boarded the subway pantless. Since then, pantless tram and subway rides have become an annual tradition all over the world.

There’s just one catch: No Pants Day can’t be commemorated in a city without a tram or subway system — so until recently, it couldn’t be imported to Jerusalem.

“I was just waiting for us to get a tramway,” Balachsan, who  told The Times of Israel on Monday evening, pronouncing the word “tramway” in a comical Eastern European accent.

“I’ve been doing it for years. I did it abroad several times, in Europe. But I’ve been waiting a long time for us to have a way to organize it [in Israel]. As soon as I finished my studies, I decided the time was right,” he said.

“Last year was the first year, when I set up the event by myself. This year, I had a bit more help. We actually set up an group, Improv Israel, to organize such events,” he said.

By “such events,” he clarified, he meant “pranks, all sorts of interesting things, spontaneous things that break the routine.”

Balachsan said that in 2012, relatively few people participated in the event. He estimated the number at 25 to 30 locals who bared their legs in public on a cold Jerusalem winter’s night.

Asked how religious passengers had reacted to passengers taking off their pants in public, Balachsan said, “I think people underestimate Jerusalem … I have lots of friends who belong to religious and other ‘oddball’ sectors, but people are great, they understand what it’s all about, it makes them laugh. They know we don’t walk around like this every day.”

Balachsan said that one Orthodox youth he knew told the participants they were lucky to have the freedom to bare all.

“People from such communities would happily join us if they could,” Balachsan said.

One two-time participant, Dima Krassovsky, told The Times of Israel that he had heard of the event on Facebook last year and had decided to participate this year as well.

“We boarded the light rail in the city center. When it began to move, everyone took off their pants and acted naturally, as if nothing had happened,” Krassovsky told The Times of Israel.

“From there, we all rode to Kiryat Moshe, got off the train and boarded a train back toward the city center.”

He said the group then split up into smaller groups that waited pantless at every station between the Jerusalem Central Bus Station and Ammunition Hill, in East Jerusalem, to board the same train and amuse passengers with their antics.

“That way, pantless passengers got on the same train at every station,” Krassovsky said.

He said most passengers reacted “nonchalantly” to the unusual sight.

“People stared, but didn’t get too excited. They preferred not to ask too many questions,” he said, adding he’d noticed Orthodox passengers giving him and his pantless friends “odd looks,” with female Orthodox passengers “not being too innocent either” and stealing a glance here and there.

Overall, he said, the reactions were positive.

“It went smoothly, there weren’t too many problems. People went with the flow,” he said.