From the episodes Batman's Satisfaction / A Piece of the Action from the 1966 Batman series.

Special guest heroes the Green Hornet and Kato go from over confident crime fighters to human stamps after Colonel Gumm shoves them into his stamp-making machine.

The viewer spends several minutes (not counting the cliffhanger at the end of the first episode) thinking that Hornet and Kato have indeed been flattened before it's revealed to all be a ruse. I would have been happy if they had spent the entire episode as stamps, perhaps being restored by Batman at the end.