Uttering nonsense that is meant to have potential comedic meaning, but is meant to be a joke and to piss off your friends or make them go crazy. This usually has strange words and phrases that people understand but don't want to hear. Like ever.
Friend #1: "Bro you totally rizzed up Livvy Dunne and Baby Gronk in Ohio. I saw skibbidi toilet there as well."
Friend #2: "That was straight brainrot bro."