The only worse person is the one who when you say "damn, I cut myself at work today..." and they reply "one time I cut myself and it was the worst thing ever." Or, if you are sick they have been sicker, if you are depressed, they are suicidal, etc. I guess, they are a one downer...
My husband's boss is a one upper and knows everything (thinks he does at least!). My husband likes to tease him about it all of the time. He (my hubby) doesn't get into all that "one upper" business. Well, not usually. Sometimes he does, but not very often. Most of the time he says he knows he's better anyway but doesn't feel the need to try and convince anyone of that fact because he already knows it's true. That man is not lacking in the confidence department, I'll tell you that!