In the ever-blurring boundary between art and stunt, Improv Everywhere's 6th Annual No Pants! subway ride got some Irish up the weekend before last.

Over 200 provocateurs did away with social convention and dropped trou, before doing like Mayor Michael Bloomberg and taking a symbolic trip on the uptown local. The mayor did not participate, and is known to be a stickler about wearing pants in public.

Among the mad men and women, were none other than some of Irish traditional music's more daring performers: Katie Linnane, Isaac Alderson and Dan Lowery, who ended up taking No Pants! to a whole new level.

When the trio arrived at Union Square -- sans pants -- they were coming from Lillie's where they play at the regular afternoon seisiún that happens there every Saturday, hosted by Cork singer Donie Carroll and Dan Neely on banjo.

1) They had their instruments with them anyway...and 2) the acoustics in Union Square can be pretty bouncy...and 3) there's plenty of floor space for sets. Keeping all that in mind, the underwear-sporting ceoltóirí took out fiddles and flutes and hit Union Square with a blast of music.

Other pants-forgoing revelers took to the ceol right away, and an impromptu céilí transformed Union Square station into a village hall.

"They were dancing everywhere around us," Katie Linnane told me, "with Gráinne Keogh showing people how to do the steps, and we got a few cents and a buck or something and then we stopped because it got too crazy -- the police were around and getting nervous about the nutty people dancing and playing Irish music with no pants on."