Justin Timberlake has been on Jimmy Fallon all week this week. The late night host calling it “Justin Timberweek.” Fresh off his 5th time hosting SNL, the pop singer has been sitting in residency on Jimmy’s couch all week.

The “SexyBack” singer did indeed bring sexy back on Jimmy’s show, but not in a way you’d ever expect: Barbershop style. Three singers joined Jimmy and Justin to complete a 5-part harmony of Justin’s popular song.

If you love the song or Justin Timberlake, you’ll love this fun version of the song!