I whistle all the time - especialy when working on my PC at home or work. These days I also find it useful to whistle whilst trying to encourge my bladder to empty. I also tend whistle when I am deep in thought - problem solving , it is probably mildly theraputic for me.
I worked in Azerbaijan and was told very firmly by locals in the office that I should not whistle - it was a sign of trouble and bad luck . As it turns out - they were right - but that's another story !!

Cheers
Betsy