Holy hickey! Has Kendall Jenner been sucking (hard) on her rumored boyfriend Anwar Hadid's neck or what?!

The little bro of Bella and Gigi was spotted in Milan at a Fashion Week event looking 1) a little dark around the eyes, 2) like a fashion nightmare, and 3) like he'd had a damn good time the night before!

Anwar, 19, and Kendall, 22, have a history together -- they were spotted at a New York Fashion Week after-party a couple weeks ago sucking face and making out at a CFDA party over the summer.

Anwar's hickey wasn't the only thing that looked a little "off" with these two today ... his un-matching shoes and socks? Kendall's knee-high turquoise cowboy boots? Paired with cut-off denim shorts and a blazer?!