Ed Sheeran is having fun on his tour, popping up in all kinds of places. Sometimes he plays music, and sometimes he just plays.
He's a big fan of South Park, so while in Denver he took Cartman's advice and went to Casa Bonita (which is owned by the South Park guys.) Ed did everything Cartman mentions in the show- he watched the mariachis and the cliff divers, and got his jail photo.