The 25-year-old actress didn't expect to be introduced to her beau Evan Peter's pals when she decided to don an electric red wig, blue eyeshadow and different coloured contact lenses on Halloween - just weeks after they started dating. Buy tickets below.
Speaking in the YouTube mini series 'Hot One', she recalled: "I went out with my boyfriend -we had just started seeing each other.
"And I met all of his friends for the first time dressed like that. He was a good sport about it. He was like, 'This is my girlfriend!' Like, he was, like, super proud.
"But I was also, like, forgot I looked like that and, like, talking to people and they were like, 'Hey...' Yeah, it was a good one."
The pop star - who has previously romanced rapper G-Eazy and rocker Yungblud - loves dating the 33-year-old actor because she finds having a different profession to her partner beneficial as she's not talking about work all of the time.
Halsey - whose real name is Ashley Frangipane - said recently: "A friend of mine -- another female artist who has been criticised for dating a lot of people -- said, 'Ashley, you need to live your f***ing life and ignore what people say about you.'
"And so now I keep everything to myself in terms of my romantic relationships. I will say that it's good to not date another musician as then your work follows you everywhere.
"Now it's my personal life so I get to go home to somebody that I love and spend time with them, and it not be about work."
In 2016, the 'Clementine' singer was diagnosed with endometriosis and she admitted the gynaecological condition has had a huge impact on her life because she was initially told it meant she wouldn't be able to carry a child.
She said: "I've been open about my struggles with my reproductive health and for a long time I thought I couldn't conceive children. Then I found out I could. My doctor told me and the room was spinning.
"It had made me feel low for ages. This had impacted my departure into womanhood. Every person I dated, I'd have to bring this up, like a disclaimer. It was both physical and emotional pain."
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