The Chainsmokers nearly brought down the house at an Ohio State frat ... and it looks like the college rager of the year.
It all went down at the SAE house ahead just before one of the biggest college football games of the season ... with OSU squaring off against the Texas Longhorns.
We're told the set was a massive surprise -- not just to partygoers, but even for the SAE frat bros, who had no idea the duo was showing up to perform.