We all know that one person whose lack of common sense makes you worry for their safety and wonder how they've made so far in life. I once had a roommate in college who called our landlord and complained that the washing machine was broken because the clothes kept coming out wet. Apparently he had never washed his own clothes before and assumed the washer was also a dryer. That same roommate once put his pet goldfish in a giant martini glass full of water, set it on the kitchen counter, and lef…