Selena Gomez was so displeased when her performance at the 2013 Jingle Ball concert went awry Friday (Dec. 6) that she cursed and stormed off the stage before finishing her set.

The 21-year-old singer took to the Staples Center stage in Los Angeles Friday night to perform in KIIS FM's annual holiday show. Things did not go as planned when her audio and microphone malfunctioned, and Gomez was heard cursing, according to E! News.

"She for sure said 'what the f--k,' ... You could hear it crystal clear," a concertgoer told E! News. The source added that it "looked like" Gomez was lip-synching and "she was messing around with her ear piece from the first song so you knew something wasn't right."

The former Disney star attempted to ease the situation by chatting with the audience in between songs.

"Sorry, the sound isn't working!" Gomez told the crowd, which was mostly filled with children, according to Us Weekly. "Are you guys having a good night? I promise, a lot cooler people are gonna come out tonight. Is it okay if I perform two more songs and you guys can get to it? ... I have to say that before you guys go on to the people that you care about, I really appreciate you supporting everything that I do. So this next song is the first song I had hit No. 1, and it's called 'Come & Get It.'"

She reportedly promised to sing two more songs, but instead dropped her mic and walked off stage, Celebuzz reported.

Singer Ariana Grande also had technical difficulties when she performed "Right There" later in the night. She apologized to the crowd, according to Rolling Stone saying, "I’m sorry the mix was off the entire time. At least you know I’m not tracked." This was apparently a dig at Gomez.

Listen to Selena Gomez drop the f-bomb below.