Kesha joined Reneé Rapp on stage at Coachella on Sunday to perform her 2010 hit song, “TiK ToK.” The chart-topping track famously features the lyric, “Wake up in the mornin’ feelin’ like P Diddy.” However, in light of the recent allegations against the Bad Boy mogul, Kesha used the opportunity to change it into a diss. She and Rapp both sang: “Wake up …