Its a crayon effect brush ^_^ I used it to make a birthday card for my lil' cusin, and decided to put it up here- hope you all like it!
As always, give me credit if you can! Arigatou!
If you've got one of the more recent (Though I'm unsure how recent) updates of GIMP, then it should take Photoshop brushes. To do so, you just download this brush here and install it just like you would a normal GIMP brush.