An obsession with the lives of others, combined with an extreme inferiority complex, resulting in a mental disorder that requires the sufferer (the Oneupman) to constantly feel the need to prove his or her self to anyone who will pay attention.

The boasts and claims of the Oneupman are actually a cry for help from an unconfident person who believes they are great simply for completing ordinary tasks faster than anyone else, possessing a higher number of certain items than anyone else, or for doing anything a higher number of times than anyone else. Sadly, the Oneupman is still stuck at the 'my dad is stronger than yours' stage of mental development.

The Oneupman never chooses a specialized activity to compete with, since they have very little special knowledge and simple 'accomplishments' appeal to them most, such as driving faster than you, eating more than you, and guessing how a movie ends before it ends. It should be noted that being the best is not the focus, the Oneupman is only interested in being better than YOU. They need others to compete with and prove themselves against, since they can't feel good unless someone feels bad.

Tellingly, the Oneupman will only compete with people they know, since competing with strangers whose skills they aren't familiar with may expose their weakness, which is the greatest fear of the Oneupman.
"Ok, in order to survive, we must both take one of these pills, and no more than one!"

"Oh yeah?? Well, I can take TWO, that's one more than you!"

"If you take two, you'll die, you idiot! This is not the time to practice Oneupmanship!"

"Oh, so you think I'm just average like you?? No way, I'm _______ (insert name here), I once _______ (insert exaggerated, unprovable claim here), I can handle two pills, ok?? Gimme those!!!"

Oneupman takes two pills and dies.
by Grackle June 5, 2009
Get the Oneupmanship mug.
forwarding urban dictionary terms back and forth with a pal, each trying to outdo the other in sending the wittiest or raunchiest term.
I sent "girthquake" to Charlie but he sent back "butt weenie." I'm gonna send that pecker head "cum bread" and win this urban oneupmanship!
by LaLaLander17 March 2, 2009
Get the urban oneupmanship mug.