I think I am actually more of an adult by now than this post suggests, but I still find this incredibly funny, especially the end: Why I'll Never Be An Adult.
Read her stuff! (Oh, except she swears as much as I do, so be forewarned.)
(Added 6/16/2011) No, no, this is the one you must read: God of Cake.
All about a small child's efforts to get cake.