"Naturally, we started talking about Mighty Mo," he said.
The more they talked, the more nostalgic they became. It wasn't long before the idea of a reunion came about.
Kehoe, who owns Antietam Gallery near Sharpsburg, decided he would host the event at his business.
Nichols, who is an artist, created an artistic rendering of the drive-up diner, as well as hot rods of their high school days in Prince George's County.
They celebrated the release of the limited edition print, "There's a Moon Out Tonight: A Tribute to the Mighty Mo," with a 1960s car show and reunion.
Six years later, the reunion has become bigger than ever, with Mighty Mo alumni attending the event from around the country.
This weekend, more than 600 people are expected to arrive at Kehoe's gallery for a trip back in time.
The event, which continues today, includes cars from the 1950s and 1960s, artwork depicting that era, oldies music and, of course, Mighty Mo food, including the famous Mighty Mo hamburger, hot fudge cake and orange freezes.
Kehoe said the food is authentically prepared using Mighty Mo recipes.
"One bite and you're back to 1963," he said.
While many people live hours away, Kehoe said quite a few attendees are transplants now living in the Washington County area.
"The reunion is a way for us to all stay in touch," he said. "And, thanks to Facebook and the Internet, word continues to spread."
"Without a doubt, Mighty Mo was an important part of our youth," said Nichols, who now lives in California.
"Gas was 28 cents a gallon and you would ride from the Queenstown Mighty Mo to the New Hampshire Avenue Mighty Mo, profiling you and your car," he said.
Nichols said he remembers driving to Mighty Mo after the Friday night football games, "riding with our school pennants flying and blowing our horns letting everyone know we had won."
"It's a different world today," he said. "Such things are lost on children who have been taken over by electronics and technology."
Nichols said he's thrilled to come back to the area and see so many of his friends, who on Saturday shared in his excitement over this year's new limited edition print, "Glen Echo Park."
"Each year, we've created a piece of art that recalls an important part of our youth," he said. "Like Mighty Mo, Glen Echo was an iconic location."
Nichols said he and Kehoe knew from the beginning that the event would be well-received.
"We had no doubt that people would love this," he said. "It transports you back to when you had a 30-inch waist and life was fine. Everybody is younger at this gig."
If you go
What: Mighty Mo Car Show and Open House
When: Today, 10 a.m. to 4 p.m.
Where: Antietam Gallery, Md. 34 near Sharpsburg.
For more information: Call 301-432-5868.