Lip-syncing hero Keenan Cahill made his late-night debut on 'Chelsea Lately' on E! Monday night, and revealed his latest YouTube masterpiece--a duet with 50 Cent. In what can only be called vintage Cahill, he bobs his head singing to 'Down on Me' by Jeremih, and at (1:21), 50 Cent steps out of the closet and joins in on the fun. All they had to do was let the camera do its magic, and now Cahill is probably the coolest kid at his school. At one point, 50 Cent even lets Cahill swag with his chain necklace on, which Cahill later admitted to Chelsea Handler was awfully heavy.

Cahill boasts over 66 million total views on YouTube, and has a catalog of fabulous camera-facing, lip-syncing video gems, featuring songs by artists like Michael Jackson, Katy Perry and Justin Bieber. Watch the whole interview and video from 'Chelsea Lately' after the jump!