Do not anger the Beliebers.
It's a lesson that's inherent to those who report celebrity gossip, but one Olivia Wilde had to find out the hard way after chastising the singer on Twitter.
After Wilde told Justin Bieber to "put a f--king shirt on" earlier this month, her account was bombarded with irate messages from riled up Beliebers.
Very intelligent and totally sensible ones, obviously. Watch below as the actress reads some of the best Tweets she received on the Tonight Show ...
Wilde also offered a preface: "This started because Justin Bieber went out without his shirt on… he was in London, and it's so cold there and I was concerned."
""I have a 19-year-old brother in London, and it's freezing! And if I saw him without a shirt, I would tell him to put it on. So I told Justin Bieber, 'Put your f--king shirt on.'"
"But I said it with love!"
Safe to say Bieber fans didn't all see it that way, and that their beloved idol has had his share of interesting incidents in London over the past few weeks.
If you recall, he had the worst birthday ever, walked around with no shirt on, collapsed on stage and threatened to f--king beat the f--k out of a photographer.
Wilde has not Tweeted about that incident ... yet. Frankly she might want to. She may be too old to be a lesbian, but she's not too old to offer advice.