Being a fairly impulsive person, I rack these up on a daily basis. Here's the complete (updated daily, most likely) collection of Ocelot's Great Lessons Learned the Hard Way, or as I like to call it OGLLHW. Gee, sounds like I need to spit that out. Anyway:

• When a trampoline says Max Weight: 150lbs, don't tempt fate.
• When diving from Stoneman bridge during a drought, you can't really do 'the flip' that fast.
• Never 'trust all content from Microsoft.' In fact, never 'trust ANY content from M$.'
• It is never a good idea to say 'I told you so' to your parents.
• Just because spaghetti and Maruchan™ soup are both good, combining them will not necessarily result in something good.
• If your mother's pet bird chews on mouse cables, don't convince her to upgrade to USB.
• A superman cape does not make you less likely to break your leg when you jump from the roof.
• Never tease a water moccasin, a bull or an officer of the law.
• Buying a pre-made extension cord is almost always cheaper than a trip to the emergency room.
• Never let the toilet seat get loose. Ever.
• Backups are not optional.
• Soap in a fountain is funny. Jello mix is not.
• Do not taunt pigeons around old ladies.
• The phrase 'heads up' ususally means 'duck.'
• Objects in mirror ARE closer than they appear.
• Do not use a cup of white gas to start a campfire.
• If the stick bends, it will not burn.
• Cooking: Just because red wine has less ABV than cognac, it doesn't mean you can safely light it with a match.