Acting out based on uncontrollable autistic or obsessive-compulsive urges; an autistic meltdown, or in a broader sense any sort of unusual behavior resulting from a psychological or psychiatric condition. See also reeee.
"I was just trying to chill, but this bitch won't stop tizzing out and making everyone nervous."
"I tried to organize the garage, but CaptainTizz here couldn't control their OCD and just ruined the last 3 hours of my work by tizzing out and stacking everything back up to the ceiling."
"Stop tizzing, you're making everyone here feel awkward and you look like a complete moron."