It’s easy to miss a friend at a concert or a football game, or even at one of the city’s multi-room bars. But it happens in much tighter quarters, too–at the Northside Grill, where just seventeen or so tables and booths are squeezed into a single room.

“We’ve actually had people who’ve sat [at separate tables] waiting for one another for like twenty minutes,” says manager David Ruby. Though the dining room is small, a few booths are tucked out of sight from the main room–and once people sit down at them, they usually watch the front door for their friend or business associate to show up and don’t recheck the other booths. Ruby says many people avoid looking directly at strangers–and so overlook friends too.

Surprisingly, mix-ups are more common on weekdays than on crowded weekends–Ruby thinks people don’t pay as close attention when it’s quieter. While most missing persons find each other within a few minutes, some are incredibly patient. One time, Ruby says, each person saved a spot for the other, seeming embarrassed about the friend who was missing in action. They waited that way for twenty minutes.

So how did they solve the MIA mystery? One person finally needed to visit the restroom–and spotted the other en route.