You can't really afford a short. So most electricians say they use plastic anti-short bushings on MC Cable because they see them as backup insurance against a short, even if they happen to be told they aren't required on MC Cable for one reason or another.
Looking online, you can find many names for the anti-short bushing including "redheads", "redeyes", and even "red devils". You can also find many ways to spell anti-short bushing, including antishort bushing, anti short bushing, and the correct way which is anti-short bushing. The red color of the anti-short bushing helps inspectors easily find the bushing. If you have any other names or uses for them, feel free to post a comment.