The act of taking a particularlysmelly shit, especially in a public restroom, leaving a stench that lasts for hours and forces others either to gag or to hold their breath until they exit the facility.
A reference to the character Reiner Braun from Attack on Titan. Reinering refers to an act in which a person gets so involved in a lie or a fake aspect of their life that they get lost up in what to believe in.
"Dude I accidentally stayed with my second family all the way until Halloween. I'm totally Reinering myself"
"Remember how Jack get pretending to be retarded? Turns out he got diagnosed with autism. Talk about Reinering yourself"
did you hear about that guy at billy's party? he wheeled some bird and took her for some rotundering, he touched her thigh but spewed and passed out before he could slip a digit and introduce her to a game of pong knuckle