So, during one of his live performances at the Summerburst Festival in Stockholm, Bieber explained to the crowd he wouldn't be singing the song.
This didn't go down too well.
"I can't do that specifically, I don't know the words... I can't do it," Justin tells the crowd.
It is then that someone in the audience throws an unidentified object at his head, and if Justin didn't duck then he would have been hit.
Justin received a lot of backlash when he previously sang the song live, and replaced the Spanish lyrics with "bla bla bla's" so he was probably trying to avoid that situation happening again. And, TBF, admitting you don't know the words is a lot better than speaking gibberish and offending people.
But as for the fan, this is not okay.
Watch the video below: