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.
"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.
y: ohhh yeaahh...you doo do yaa (he (y) doesn't like her but just wants to ruin the chances of them getting together, so behind (x's) back gets her (Kati) to go out with him, X is annoyed about them getting together but pretends its not bothering him, meanwhile X is using the same M.O 'method of operating' to get one back.
The one-upmanship escalates until either one stops, or they realise there both at it..(which would quite amsuing for them, or embarrasing.. depends how you take it ;)