You couldn't be more wrong. Cincy was using "WHO DEY" years before the Saints started saying "Who Dat".
We were yelling the WHO DEY chant in November of 1981.
Saints didn't start chirping out WHO DAT until 1983. Then it went away for awhile, but it resurfaced in 1987 during their playoff run. The Saints WHO DAT got some publicity because they were in the playoffs and the Bengals made their Super Bowl run in 1988 - so everyone thought the WHO DEY chant they were hearing from Bengals fans in 1988 was copied from the Saints from 1987 - but that wasn't so. It never left Bengals' fans mouths from 1981.
Actually, it is very probable that the Bengals started it in 1981, then LSU changed it to WHO DAT during their Orange Bowl run in 1982. Then the Saints adopted it as their battle cry.
Make no mistake - WHO DEY is a Cincy chant - and a Cincy chant alone. As ignorant as "WHO DEY" might sound - it's ours and ours alone.