"Man, times are tough. The economy is so bad that David Letterman is buying jokes online for $100 each. He might get more for his money by finding an online date."

OK, that was a cheap attempt at humor, and a cheap shot at Letterman, who often makes fun of himself. But Letterman, and other late-night TV hosts, are doing just that -- paying freelance writers $75 or $100.

But the catch is they only get paid if their joke appears on the air, and they aren't paid union wages, according to a Los Angeles Times story.

Freelance writer and Web developer Phil Johnson told the Times that from his home in Boston he has gotten more than 160 of his jokes on the "Late Show With David Letterman" and, before that, "The Tonight Show With Jay Leno."

Here's one of Johnson's jokes that was telecast on Letterman's March 17 monologue, which is archived on Letterman's Web site and can still be watched. "Beautiful day in New York City," Letterman said. "Am I right about that? A gorgeous day. It was so nice today that AIG gave a bonus to Al Roker."

The underground network of comedy writers can make a quick $100 or so by e-mailing jokes to the shows, but only if their joke runs on the air. While $100 is nothing to turn away, especially in a recession, the paid union members earn a lot more -- $3,215 minimum for writing a comedy sketch under 10 minutes.

Some shows, such as those of Jon Stewart and Conan O'Brien, don't hire freelance writers. O'Brien doesn't because he supports the guild, which will leave some freelancers out of extra work when he takes over for Leno on June 1.