I am not sure at what age it starts...the whole need to one-up someone but I can tell you it is ever present in 3rd graders. I am guilty of it. It is one of those rotten things we do when we want to feel better about ourselves or not feel jealous of someone. We try to one-up them. Sometimes it is on accident. You hear someone say something and it reminds you of a story and it kind of turns into a one-up. Oh well.
I've been fortunate enough to listen to 3rd graders one-up eachother this week. Mainly talking about their holiday break plans and gifts they know or think they will be receiving. Enjoy the example below.
Girl 1: I'm getting a phone.
Boy: I've already got a phone.
Girl 1: Well im getting an Iphone.
Boy: Well my dad already got me a phone, they arent that expensive or anything.
Girl 2: I want a phone.
Girl 1: Oh and I'm getting an Ipad. I mean I have an Ipad.
By the way in case you didn't know...3rd graders are 9 years old. 9! I'm pretty sure I got a pager at 16. A phone at 19.