Foolish or senseless behavior.
Buffoonery Clowning Frivolity Harlequinade Japery Prank acting like a clown or buffoon.
Behavior Behaviour Conduct Doings manner of acting or controlling yourself; "His conduct is inappropriate".
Anserine Dopey Dopy Foolish Gooselike Goosey Goosy Jerky having or revealing stupidity; "A dopey kid".
Nitwitted Senseless Soft-Witted Witless (of especially persons) lacking sense or understanding or judgment.