Taylor Swift & Gigi Hadid -- Girl's Day Out (PHOTO)

Taylor Swift and Gigi Hadid continue to be bffs -- and we continue to be jealous -- hanging out in L.A. together on Friday.

The two were spotted in Beverly Hills on their way into a nail salon ... and we gotta say, for someone who had a suspicious man was arrested outside her house just a couple days before ... Taylor doesn't look too concerned.

It's unclear where the rest of Swift's best friend squad was ... but one thing's for sure, we want in.