CHICAGO (CBS) — A Craigslist message sought to find the man who fathered a woman’s unborn baby in a bathroom at the Aragon Ballroom.

As WBBM Newsradio’s Mike Krauser reports, the ad was posted in the Craigslist “missed connections” section on Monday. It has since been taken down, but the Next Web has posted a screen grab.

LISTEN: WBBM Newsradio’s Mike Krauser reports

The posting is from a 28-year-old woman who describes herself as having “blue hair, silver tube top, knee-high black biker boots,” and the man at whom the ad is directed as having a “red mohawk, black pentagram gauges, viper piercings.”

The woman says she was “grinding” the man in the pit during a Megadeth and Motörhead concert at the Aragon, 1106 W. Lawrence Ave., and afterward, they went to the restroom and had sex in a stall. The ad describes the sex in graphic detail, and points out in slang terms that the sex was unprotected.

“You were really good and you had to gag me so I would(n’t) make too much noise,” the posting said.

At the end of the posting, the woman writes: “Anyway, I’m pregnant. It’s yours. Contact me if you want to be part of your child’s life.”

Since it was posted, the ad has been the subject of an article in the Chicago Sun-Times, and has appeared on various social networking sites.

The blog Chicagoist speculated on whether the ad was real, pointing out that “the brutal lack of transition between the tantalizing details of the hook-up to ‘anyway, I’m pregnant’ suggests a comedic mind at work.”

If the ad is fake, Chicagoist said, “No harm, no foul, and we all get to laugh at metalheads.”

If it is real, Chicagoist says, maybe people shouldn’t be laughing at the ad.

“(P)erhaps we should reverse the flow of this conversation, Chicago river-style, from uncomfortably laughing at the ribald nature of it all to something resembling, oh, I don’t know, human decency, concern, or why the f**k not, empathy,” the blog said.