I can whistle in three different ways. The classic pursed lip whistle, a whistle using just the tip of my tongue and the roof of my mouth, not using my lips at all, and then another using the tops of my bottom teeth. I can make decent bird sounds using my bottom teeth, but I can do pretty much any tune I can think of with the pursed lip method. It has been relevant to my life exactly zero times, except to entertain myself.