• Danish Translation
• French Translation

Martinez told Fuse:

In my life, this is when I started talking to a new boy. It was really hard for me to explain or tell him how I felt, because I was scared of how he would react, so I just felt like I needed to wash out my mouth with soap, and constantly hide how I felt.

She also told ELLE in July 2015:

‘Soap’ was written about my current boyfriend when we were first talking. I felt too scared to say how I felt about him and thought if I told him it’d be like throwing a toaster in his bath. So I washed my mouth out with soap. I think anyone can really relate to this song. I’m sure there was a time in everyone’s life where they felt too scared to say how they felt so they ‘washed their mouth out with soap.’

Warren shared on her commentary playlist, “Write on Track”:

What I love so much about Melanie is, she has such a clear, solid vision for her artistry and what she wants everything to sound like, look like, writes and directs her own videos and she's—she’s just the best she’s really quite creative and it’s fun to work with her, ‘cause she knows exactly what she wants. In this session, we went in with the idea of washing with soap and Melanie had some personal stuff going on at the time, that conceptually lined up. We were like 'What if we make a drop that sounds like soap bubbles popping?’ And Kyle Shearer, the producer was like ‘Oh, hell yeah!’ And so he crushed it and made a crazy beat and it turned into this song.