The Grammy winning singer flashed a grin before he sees the camera and immediately goes back to cold Kanye with a steely look.
West, 37, was at the playoff game between the Cleveland Cavaliers and the Chicago Bulls to perform his new song "All Day."
The vine of him smiling now has almost 8 million loops.
West has said in the past why he doesn't smile for pictures or much in public.
"Back when I was working on Yeezus, I saw this book from the 1800s and it was velvet-covered with brass and everything," West said in a speech at a fashion event in January, according to E! News. "I looked at all these people's photos and they look so real and their outfits were incredible and they weren't smiling and people, you know the paparazzi, always come up to me, 'Why you not smiling?' and I think, not smiling makes me smile. ...When you see paintings in an old castle, people are not smiling cause it just wouldn't look as cool."