When throwing a bag of trash into the communal dumpster, be sure your keys are in your other hand, or in your bag, or in your pocket, or on the ground, or basically anywhere that is NOT the hand tossing the garbage; otherwise you may find yourself joining the flies in the dumpster rooting through some really nasty stuff in search of said keys.

This is an especially good thing to keep in mind during particularly hot spells or when it is almost garbage day and the dumpster is very full.