> #1: When your soda is just about gone, and you figure you'll just chug down the remainder in one gulp.

A related one: when you're absently drinking a soda while doing something else, think the soda can is still mostly full and pick it up only to discover it's almost entirely empty -- but that you picked it up with the amount of force for a full can, but now it's empty and thus much lighter and your hand goes flying.

Stephen