Big Wolf on Campus (1999)

S2E8 Imaginary Fiend

Merton is busy gathering toys for a local charity drive when his childhood imaginary friend, Vince, suddenly reappears. Vince is fascinated by how much Merton has changed and eagerly helps with the collection. But when Merton accidentally angers him, Vince snaps—flying into a violent rage and wrecking everything in sight.