His lip-sync to Katy Perry’s Teenage Dream alone has more than 15 million views.
But he received some serious star-power in the flesh as he appeared on Chelsea Lately, with US comedienne host Chelsea Handler.
Handler, with the help of her rumoured boyfriend 50 Cent, arranged for the rapper to appear in Cahill’s latest internet funny.
After starting the video on his own, Keenan was joined by the hip-hop star mouthing and dancing to his track Down on Me.
Cahill, from Chicago, told Handler he had become well known for the videos in his school.
“One day I was going to lunch and someone came up to me and asked if they could get a picture with me – I was like, ‘Ok!’ I’m not going to say no!”