One Direction fans are Watch Sweet Alibis Onlinestaunchly protective of their beloved band members, something an Australian radio host is learning the hard way.

Former 1D member Louis Tomlinson has generated pretty abusive backlash against an Australian radio host, who made a passing joke about his facial hair.

Hit Network host Ash London called Tomlinson's beard "ratty" on air, joking with fellow co-host Ed Kavalee and guest Ash Williams on her show Ash London Live. "He's not Harry Styles," said Kavalee, who also called him the "least popular one." Williams called him "the guy with the smaller face with the short brown hair."

Fans didn't take too kindly to the comments, and barraged London with hate on Twitter (not so much her co-hosts).

London apologised on Twitter, before setting her account to private for a brief time, in an attempt to stop the wave of harassment online.

This Tweet is currently unavailable. It might be loading or has been removed.

This, of course, isn't the first time Tomlinson's fans have taken up arms to defend the singer — Twitter troops rallied when he was arrested in March, after allegedly pulling an overbearing paparazzo to the ground at LAX.

Tomlinson responded to London a few hours later, tweeting to his 31 million followers:

This Tweet is currently unavailable. It might be loading or has been removed.

To be honest, the only thing London said of Tomlinson was a comment on his facial hair. Sure, it's a pretty mean thing to say, but London's male co-hosts haven't received nearly as much backlash, and their comments were much, much nastier.

Here's the actual chat:

This Tweet is currently unavailable. It might be loading or has been removed.

London is taking a break from social media after receiving "abuse and threats," as she posted on Twitter on Tuesday.

This Tweet is currently unavailable. It might be loading or has been removed.

Making fun of someone's appearance isn't a very nice thing to do, of course. But being abusive and actually threatening someone for making a comment about someone else's beard? That's next level.