Just when you thought you were starting to understand fashion ... in cometh the 2017 Costume Institute Gala at Metropolitan Museum of Art.

But just because you have no idea what's going on in the fashion world doesn't mean you can't gawk and, way more fun ... judge.

It's probably the most fun event of the year in New York City ... hands down.

Check out Kendall Jenner's buns, La La Anthony's sheer style, Katy Perry's gnarly look, Jaden Smith's hair-raising accessory choice and tons more.

And check out the epic selfie Kylie Jenner snapped in a bathroom -- Kim, Diddy, Kendall, Paris Jackson, Frank Ocean, half a Chrissy Teigen and more. In yo' face, Ellen