Why The Bachelor's Keira is always licking her teeth.

If there’s one person who’s been dominating this season of The Bachelor, it’s Keira Maguire.

From her love of chokers to her unfailing ability to always say exactly what she’s thinking, she’s the contestant who’s got everyone talking. And that was before it emerged she was born into a cult.

Aside from her epic one-liners, there’s one other habit viewers can’t stop watching. Her teeth-licking.

Image: Channel 10/Screenshot

At the cocktail party, while she's dancing, on group and single dates, during her piece to cameras - it doesn't matter where she is or what she's doing, you can guarantee that at some point her pout will be interrupted by a quick lick of the teeth.

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It's almost become a signature move. But exactly why she does it - although some have suggested it's an "aggressive tic" - has remained a mystery. Until now.

Former contestant Rachel Moore, who was an 'Intruder' in the last season, shared her convincing theory with Mamamia on the Bach Chat podcast last night. (Post continues after audio.)

If she's right, then Keira definitely gets the last laugh.

"I don't know her personally but I'm going to have to say, and I did this as well, she's always licking her teeth because she's got lipstick on and she doesn't want lipstick on her teeth!" Moore said.

"There's a camera there, she's about to say something, or she's preparing to be shot so that's why she licks her teeth as she's thinking, 'Right, got to make sure and double check I don't have any lipstick on my teeth before the camera pans on me'."

Image: Channel 10

"I don't think it's something she does all the time in everyday life."

So there you have it. A simple move to prevent the dreaded lipstick-on-teeth look on national TV.

Here's a reminder of who's still in the running. Click through the gallery:

Image: Channel 10/Screenshot.