My parents used to call and/or text me and my sister when we were all at home.
Have you ever seen The Sound of Music? Captain Von Trapp uses a whistle with distinct signals to call his kids. In the film/stage show it just makes him seem like a stern guy, but apparently in real life he did it because the estate was really large and the captain himself had a weak voice.
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http://img.photobucket.com/albums/v129/ukealii50/kylo.jpg - Thanks uke!
http://img193.imageshack.us/img193/829/07kyloforce.png - Thanks Diyosa!