Bathing with your mic is a bad idea.
Dropping mics off of tall buildings is not advised.
Dousing your mic with kerosine and igniting it would probably do more harm than good (unless it's a Behringer).
Your mic is not dishwasher or microwave safe.
But seriously, the main ones have been covered. Blowing into a condenser or ribbon mic is bad. Loud noises usually won't do harm unless they are accompanied by a blast of moving air (mouth, speaker, drumhead, etc.). Dynamics are usually pretty rugged and can handle these things better. Dropping them or hitting them with drumsticks is no good.