Somebody edited together a bunch of the "I Feel Good" scare pranks. If you're not familiar, the prank is done to a friend or relative who's minding their own business.
You blast the opening scream and verse of James Brown's "I Feel Good", and watch their reaction. They usually jump and do their own scream.
(Warning: There are profanities in Spanish, and someone flips the bird in the video. Funny moments include the "scolding guy" at 0:47 . . . the "throwing shoe guy" at 2:10 . . . and the woman yelling back at 2:24.)