The Max Headroom Incident

On November 22, 1987, an unknown group of people hijacked a WTTW re-run of the 1977 Doctor Who serial "Horror of Fang Rock" using a pre-recorded video parodying the Channel 4 character Max Headroom. The video, which features "Max" erratically mocking various bits of pop culture before being spanked by a French maid, aired for 90 seconds before cutting back to Doctor Who. To this day, the parties responsible have never been identified. Note: this clip has been edited for conciseness.

Example of:
Mock Headroom