Britney Spears and newish beau Sam Asghari are taking things slow, publicity-wise. First, they were revealed by mistake on his Instagram . Then, paps spotted them having lunch with Spears' friends . Finally, they transitioned into Instagram official territory . Their Snapchat filter-off was just icing on the cake. Spears says that their romantic relationship is all due to some on-set weirdness during her "Slumber Party" video. She gave her most detailed account yet of the relationship while speaking on Dallas radio. The show in question was. CBS Radio's Fast in the Morning With Nathan Fast."I think we were at um…we were shooting," Spears said, according to ET . "We were doing the scene where I was doing the walk scene through the hall to go through the door to go to the bedroom and we were sitting there and waiting and waiting together for like 20 minutes at a time. We were having to be literally stuck there together, so we were basically forced to talk to each other." She says that they were talking about sushi. And Asghari, super casually, suggested that they should get sushi. Haha, that's barely even a date. Just totally casually. "So it wasn't even a serious thing," Spears said, according to ET . "It was one of those things that we were having a conversation to get through the experience, you know? I kept his number, and it was so weird -- it was like five months later, and I found his number in my bag. I was like, 'He is really cute. This guy is really cute.' So then I called him, and ever since then, he is just a really fun, funny person." Well that sounds simple enough. Just become a male model, get cast in a music video, and bam! You're dating Britney Spears.