Glenn had big ideas when he and Gary started their joint cartoon, imagining the brothers would punch the clock together and work side-by-side in the same studio. He even reorganized his home studio space to install an extra drawing board and computer.
Baby brother's hopes were dashed, however, when he realized Gary is usually getting out of bed around the time he breaks for lunch.
"I joke, it's like having a brother in Europe," he said.
Glenn has to wait until 4 p.m. to phone Gary about work. Their houses are only a few miles apart, but they live in completely different biological time zones.
They do work together, however. Glenn said he and Gary talk every day to bounce ideas around and ask each other's advice.
"We show each other the cartoons after we're done and laugh at them," Glenn said. "When we do our cartoons we're not trying to fill any niche. We're really just drawing what makes us laugh."
Sometimes the jokes are based on things that happen to the brothers in real life. Glenn carries a notepad around, so he's always ready when inspiration strikes. He keeps a notepad on his nightstand, too, in case the muses decide to wake him up. Sometimes, he just begins doodling and ideas "sprout out."
Gary's writing process sounds as unconventional as his sleep schedule and office hours.
"He said 'I've found if I sit and I'll laugh out loud, then I'll backtrack and try to think of something that would make me laugh.' That's the most messed up writing style I've ever heard of," Glenn said.
But it works.
The National Cartoonists Society gave "The Flying McCoys" the award for "Best Newspaper Panel Cartoon" in 2011. Glenn said he and Gary also get many letters from fans, plus a lot of support on Facebook.
"It's gratifying. I feel really lucky," he said. "('Peanuts' creator Charles) Shultz had a quote - Gary told me about this - Shultz told him, he doesn't like to refer to what he does as work. He feels so lucky, he doesn't want to bring bad luck down on him.
"It definitely beats digging a ditch."
And, coming from a man who works alongside a bar bouncer-turned-black humor cartoonist, we'd better believe him.