The Chicago Tribune reports the going rate for a one-liner sold to one of the late-night talks shows these days is $75 to $100 – usually paid by check with a note in the memo line reading “one joke.”

Known colloquially as “faxing into a show,” because the jokes were submitted by fax until e-mail became ubiquitous, freelance joke writing has been a fixture of late-night television, quietly flourishing for decades. It is widely acknowledged in the industry that jokes told by Leno, Letterman, Jimmy Fallon or SNL’s Seth Meyers might originate with a wannabe joke writer and not with a credited Writers Guild of America member.

Sounds like a pretty sweet gig, right? Except for that “not with a credited Writers Guild of America member” part. That sounds like trouble. It is – and – it isn’t.

It turns out enforcement of the rules is very, very tough, especially since the shows who use freelancers are unlikely to cooperate when someone blows the whistle.

“Any time someone has made an allegation, we’ve tried to investigate it,” said Patric Verrone, president of the WGA, West, an ex-writer for Johnny Carson’s “Tonight Show.” “The problem we run up against is that the show denies it happens, and the writer who did it won’t come forward to provide us with concrete evidence.”

“Concrete evidence.” You mean like Phil Johnson, a freelancer and Web developer, who sends in dozens of jokes each week and posts the ones that end up getting used on his Web site, Chumworth on the News? That seems like a pretty easy trail to follow, even for the WGA.

So what’s the main argument against freelance joke writing? It takes money away from the guys who play by the rules.

“It’s a question of really maintaining employment opportunities for guild writers,” said Lowell Peterson, executive director of the WGA, East.

One late-night host who refuses freelance jokes is Conan O’Brien, which has presented an interesting question as he prepares to replace Jay Leno, who uses freelancers. Will O’Brien continue to play by the rules or bow to pressure and continue the tradition on “The Tonight Show”?

Read the Trib’s complete story on the joke writing underground here.

Wednesday, May 6
Jo Koy, Natasha Leggero – “Chelsea Lately”
Ben Harper & Relentless7 – “Late Show with David Letterman”
Van Morrison – “The Tonight Show with Jay Leno”
The National – “Late Night with Jimmy Fallon”
Black Eyed Peas – “Jimmy Kimmel Live!”
Zac Brown Band – “Late Late Show with Craig Ferguson”
Bobby Ray – “Last Call with Carson Daly”

Thursday, May 7
Jen Kirkman, Randy Sklar, Jason Sklar – “Chelsea Lately”
Faryl Smith – “The Bonnie Hunt Show”
Norm MacDonald, Animal Collective – “Late Show with David Letterman”
Ben Harper & Relentless7 – “Late Night with Jimmy Fallon”
Flo Rida – “Jimmy Kimmel Live!”
Black Kids – “Last Call with Carson Daly”

Friday, May 8
Whitney Cummings, Kevin Hart – “Chelsea Lately” – rerun
Diana Krall, Lewis Black – “The Hour with George Stroumboulopoulos”
Brian Regan, Chris Cornell – “Late Show with David Letterman”
Jewel – “The Tonight Show with Jay Leno”
Joan Rivers – “Late Night with Jimmy Fallon”
Scott Weiland – “Jimmy Kimmel Live!”
Ida Maria – “Last Call with Carson Daly”

Saturday, May 9
Lyle Lovett, John Hiatt, Guy Clark, Joe Ely – “Austin City Limits” – rerun
Justin Timberlake, Ciara – “Saturday Night Live”