Lacking in appropriate attire! Kristen Stewart joined Tonight Show host Jimmy Fallon in a hilarious game of Jell-O shot Twister on Monday, July 11 — despite the fact she was wearing a pair of tiny jean shorts and a loose crop top!

The 26-year-old actress tied her jacket around her waist in an attempt to cover up a little more, before she and Fallon got ready to challenge one another in a drunken version of the classic game.

"When you put your hand or foot down, you have to take that shot," Fallon explained to his guest, of the multicolored Jell-O shots adorning each of the colored squares on the Twister mat.

First up, the spinner landed on yellow, and the duo placed their left hand on the appropriate circle, before downing their first shot.

"These are gargantuan shots!" the Equals star (who was showcasing her new haircut — the first she'd ever worn that wasn't for a role) exclaimed.

Things went smoothly at first, but as the game progressed and the shots became harder to grab and swallow, the Twilight alum started to protest.

"I'm really full!" she complained as yet another Jell-O shot was passed for her to chug down.

Watch the whole funny clip in the video above, and find out who lost their balance first!

Can't get enough of Us? Sign up now for the Us Weekly newsletter packed with the latest celeb news, hot pics and more!