Bono, the lead vocals and rhythm guitar of the band, first appeared in the Season Eleven episode, "More Crap", where Randy Marsh temporarily beat Bono as the record holder of the "world's biggest crap".
Furious at Randy beating him and making him "number 2", he then proceeds to take a massive crap of his own, beating out Randy.
It is then revealed he literally is the world's biggest crap and that he was once taken by a ranking member of the EFSMB. He was transformed from crap into a human being when a board member fed him breast milk from his own chest.
In "#HappyHolograms", U2 was said to have performed in the Washington Redskins: Go Fuck Yourself Holiday Special, but they only appeared in the promo.