Kanye West's 'Yeezus' was notable for a number of reasons: its marketing strategy, its unorthodox production style and its lack of an album cover, among other things. Another interesting aspect was its list of collaborators. There wasn't just industry heavyweights; West showed love to the newcomers too, with the inclusion of Chief Keef, King L and Travi$ Scott.

West continued to do so last night (Aug. 1), when he surprised the audience at a Travi$ Scott concert with a guest appearance. The El Rey Theatre audience went into complete chaos when he started his performance of 'New Slaves.'

Travi$ Scott lost his mind, too. He threw off his shirt and started crowd surfing as West delivered his verses. It looked like a wild moment, and surely was a memorable one for all in attendance.