It confused a lot of people when 2 Chainz starred in Fall Out Boy's video for 'My Songs Know What You Did in the Dark (Light 'Em Up)' video, but now it makes sense.

The recently-arrested rapper joined the band onstage for their performance at the NBA All-Star Slam Dunk contest for a remix of the track, and they killed it.

2 Chainz hopped onstage before the second verse, announcing his presence with the requisite "2 Chaaaaaainz!" Promptly, the beat dropped and he spit his own verse, then lingered around onstage to sing along with Pete Wentz. Based on both their performance and everyone's coordinating jerseys, we really hope 2 Chainz joins them on tour. They're perfect together!