Cam and Mitch are up to no good! Modern Family couple Jesse Tyler Ferguson and Eric Stonestreet visited Kansas State University recently for work, and ended up bar-hopping, crashing a frat party, and walking in on a couple having sex.

Ferguson, 38, sat down with Conan O'Brien on Tuesday, Sept. 30, to explain the sequence of events. The stars dropped by Kansas State (Stonestreet's alma mater) for a Q&A about the TV industry, and bar-hopped in the college town after work. Their night began to spiral at 2:30 a.m., when Stonestreet, 43, suggested they visit his old fraternity house.

"We knocked on the door, 2:30 in the morning," Ferguson recalled. "They opened the door, and there are these two people from television — iconic characters if you ask me — and they were like 'What are you doing here?!'"

The ABC sitcom stars then meandered through the halls of the "disgusting" frat house, found Stonestreet's old picture, and decided to see his old room.

"He just opens up a room that he used to live in," Ferguson recalled of his costar. "And there was a man in there with his lady friend and they were under the sheets doing naughty things, and we come into the room, and they're like, 'Heyyyyyyyyy!'"

The couple then asked the stars to take pictures with them, which Ferguson shared on the show (faces blurred, of course).

Watch the funny video above!