People that think they know everything there is to know about everything.....
My discussion with another co-worker: "I've been doing P90X off and on for about a year now. I'd like to dedicate myself more to it, but life sometimes interrupts and I find myself not being able to dedicate myself completely to it." Co Worker's response: "So do you think that it actually works?" Before I could even generate my response that I've lost about 2-3 inches in my waist and have actually seen decent muscle growth, another co-worker (with a LARGE GUT that hangs over his belt and no obvious signs of any level of physical fitness) pipes in, "P90X is useless". I just replied, "It works for me" and walked away.