Harvey Levin -- TMZ Staff Gets Revenge During ALS Ice Bucket Challenge

Never has the TMZ staff so quickly assembled for an outing ... lining up to douse Harvey over ... and over ... and over.

More than a dozen staffers double-fisted sippy cups filled with the cold stuff for the ALS Ice Bucket Challenge.

When the cups were empty ... the staff wanted more ... staging a coup.

The challenge has been the most successful campaign in memory, raising almost $23 million.

You gotta watch the video and hear who Harvey nominated for his challenge.