A term created and popularized on the online community of AoPS, DChen is the name you give to a mathlete who wins the math competition ARML both individually and by being on the winning math team. Alternatively, due to stereotypes about mathletes, it has more recently been used to describe anyone on AoPS who is below the height of 4 ft 8 (see dwarves).
Man, I just won ARML this year as a team and individually. I totally just pulled a DChen.
*shrinks 10 inches*
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.