When a person ingests too much mdma or ecstasy at a party and subsequently becomes ridiculously high to the point of their eyes rolling into the back of their head, their jaw uncontrollably moving and ultimately having no sense of where they are. It is also characterized by repeated stroking of soft objects such as cats and furniture all while having no idea of what is going on
Jim: "Did you talk to Kyle last night? that kid was so fucked up on molly"
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).