It started out last week as a senior class prank: attempt to lure random teachers into an impromptu dance battle after school in Chicago's Whitney Young High School lunchroom.
One teen, encouraged by his peers, danced across the room, spotted his unsuspecting target and showed off his footwork skills in the doorway of a teacher's office.
When the teacher didn't bite -- just clapped as the student danced away -- the student's sights were set on John Fanning, the school's dean of students.
After revving up the crowd with a few more moves, the teen sprinted and landed directly in front of Fanning, letting him in on the battle with the fanciest of footwork within inches of his face.
Fanning didn't miss a beat. He broke out into an Irish jig, to the erupting cheers of the lunchroom.
The video has since gone viral, attracting nearly 200,000 views Tuesday and even landing Fanning network interviews. The video's author posted that the prank "turned into a party on Whitney Young's 2nd floor the minute Mr. 'Thirst Gawd' Fanning decided to be the first person to strike back. Shout out to that man Norris, '13 ;)"
Fanning told the Chicago Sun-Times the dance wasn't planned, though he felt the buzz of a potential senior prank being planned.
As for his Irish dancing skills, Fanning says they're legit. He attended dance classes as kid at St. Ignatius Catholic Church after school.