Demi Lovato hat earrings cross shorts daisy dukes legs heels necklace feather denim bracelet black purse ring face paint glitter

Let's face it -- pretty much EVERYBODY's a fan of Katy Perry, even fellow pop-stars like Demi Lovato.

The singer took in Perry's concert Friday in LA ... perhaps taking some pointers from the multi-platinum recording artist?

Demi wore some Supernatural sparkles paint on the left side of her face and some monster crucifix earrings along with her short denim cut-offs and booties.

Lovato just released her new single Skyscraper to good reviews, but topping the charts like Katy's Last Friday Night or any of her other #1 hits, is no easy feat!

Guess what other singer we caught up with at Katy's concert -- click through to find out ...