I heard a story from an old ex-ranker when I was on IOT but this might just be an urban legend.
Apparently an airman was sauntering across the parade square after breakfast, hat off and so on. A Warrant Officer spies him from way over the other side of the square and shouts “AIRMAN!!!”
The airman looks round and, seeing how far away the warrant is, shouts back “WARRANT OFFICER!!” and runs off!
Legend.