I only have the base game and Seasons at the moment and I'm pretty sure this hairstyle is a default one but I can't find it anywhere in CAS, even using the unlockOutfits on cheat!!
One of my Sims had it by Default but I changed it because I didn't like it at first but then I created a style for it... Some NPC also have it, like this one of the photo (made him join my family on purpose to see if I could find it but no luck =/ )
I know there are similar ones but they are not the same, help is much appreciated, I'm sorry if this was posted here already but I couldn't find it. Nor the list of default content of the game, only customized ones =S
Thanks in advance and take care* =D

I think that this is actually an error or glitch as this hairstyle is for females. It's the one Cornelia Goth in Sunset Valley wears by default.

Well, now that you mention it my specific Sim had female hair when he was a Toddler and Child (the paper girl hairstyle) so you're probably right! O.o
Thanks anyway, at least I can move on now and stop searching like crazy =P