NES.
Super Mario Brothers 1. Level 1-2, the end of the underground segment of the first underground level. Walking atop the brick ceiling (attained through
elevator abuse) takes you to the first
Warp Zone but this is more insidious and considerably more interesting.
Standing on the lip of the big green pipe that takes you aboveground to the flag... and FREEDOM! you jump-punch the first (er, left-most) ceiling-constituting brick-block. Then (this will take several tries) you jump, facing left, trying to occupy the space the recently-punched block did, but at the last minute you lean right and are juxtaposed, occupying the same physical space as the bunch of bricks next to it.
Instead of an explosion (as conventional physics imagines such an event) you are squeezed inexorably righter, righter like the pit of an olive in some obscene masonry peristalsis through the ceiling and are popped out where the Warp Zone usually is.
But it's not the warp zone anymore - now it is a pipe that takes you to MINUSLAND!
Minusland is an inordinately long aquatic level that requires eight completions, at which event it will drop you off at the very last level of the game (8-4) in considerably shorter time than the conventional routes or even with advantage of the conventional (warp zone) short cuts.