Joey Fatone -- Chick Fans Show Topless Love

Hollywood got all 1998 on Joey Fatone last night, and it was spectacular -- as a simple photo with 2 female fans turned into an exhibition of nipple piercings.

Joey was walking out of Beacher's Madhouse in Hollywood when a convo with him about Britney Spears was thankfully interrupted by a couple of adoring fans ... who asked our camera guy to snap a pic.

One girl immediately says, "I was going to show you my nipple piercing" -- and even though Joey says that's not necessary ... sometimes s**t happens.

Three awesome reasons to watch this clip: 1) The girl who flashes her boob ... 2) Joey squirming while it happens .... and 3)see reason#1.