Really.
Six day riders used to slow that way during the Madisons when the chase was going full gas and they wanted to cut the time waiting for their team mate to come round and throw them back in again. Not something you see today, but on winter clubruns back in the day when most of the club would be on fixed it was a way of showing off how cool you were.
As was pedaling with one foot and resting the other on the inside of the handle bar bend, again copying the pros who used to do it during the long neutralised periods in the sixes - often while reading a paper. I never saw anyone come off doing it either, though the older riders used to administer a stern warning if it went on too long. It is amazing the amount of control a fixed gear gives if you learn to use it.