Fairly simple, the someone posts their own personality traits and the nexts poster names an Anime character than is the most like them!

Like this:

Stubborn, Perverse, Mean yet Smart and Nice towards my friends

Lina Inverse.

I'll go first:

Love my friends, mean to people who are arseholes, and love being outside.

Uh... Umi from MKR.

Quick-witted, lively, honest.

umh...ed from fma? XP

quiet, at times really crazy, dreamy...

Fuu from MKR! Hey... She can be crazy, too, ya know.

mean-spirited but tender heart?

Haruko from FLCL

Happy go lucky, childish, never quite

Tsuzuki Asato form YnM.

cat-like, happy, powerful, loving.

Vash Trigun

Comic relief type, never does anything right, always the wrong place at the wrong time

That crazy blonde girl from Excel Saga.

blooc-sucker, eternal body, brown hair.

miyu from vampire princess miyu

friendly, smart, kind, sometimes too sincere

Lacus Clyne

Dreamer, quiet, easily ticked off if I lose on just about anything.

Arisa from Cat Girl Nuku Nuku

genius, black-haired, snotty, little sister

Hatoko Kobayashi from Angelic Layer

cute, blonde, clumsy

Misuzu (in Air)

Honest, loyal, and too lazy