/whistle and some basic emotes

There was once a /sing command, I believe, in the game, which would give you the music key interface just like instruments. There would be great if there was a /whistle command that allowed you to do the same; to whistle a song.

Plenty of emote suggestions have been done before.

But, a couple of basic ones that could be used both by players and NPCs,
/yawn
/cough (fist to mouth)
/sneeze
/nervous (nervously looking around)