No joke! With all the messing around I've done with survival whistles, my daughter has adapted a kind of ongoing joke where when I blow a whistle, no matter where she is or what she is doing, she'll immediatly stop and come running to me in a pretend state of excitement (like a dog who thinks he'll get a treat).

Hey, whatever works to get their attention. <img src="/images/graemlins/smirk.gif" alt="" />