Okay, I'm confused and feeling VERY thwarted.
I made a simple head accessory. I cloned the Supernatural necklace so I could use its transparency map. The only joint I assigned it was the hat slider, and it's low poly, around 1000 or so.

WHY is it that it's exploding in-game, even though it's not using any morphs? I made ton of accessories and never had this problem; what happened, please? Did my noobness have another outbreak?

I still don't know how what I did wrong or how to fix this -- I ended up adding morphs to the stupid thing, loaded it in game, and while the explosion was lesser than before, there was STILL morph explosion
I don't understand -- I never added morphs to accessories before; especially ones that go on the head -- the hat slider joint always compensated for that, so I have ZERO idea what's going on, especially since it's a low poly mesh in the first place. *trying hard not to contemplate simmicide*

You know what? Eff it. I reassigned the bloody thing so it uses the b-head-new joint instead, and got rid of all the morphs. If this doesn't work I'll just assume the mesh is cursed, cuz this is crazy.

UPDATE: The mesh is cursed. NO CHANGE.
What the actual eff.

I'm a stubborn git, so I'm gonna keep trying to fix this stupid thing.
I am gonna try using the method mentioned here: http://www.modthesims.info/showthread.php?t=512867
Pray for me, anyone out there looking down on me from above (and no doubt snickering at my expense).

[UPDATE]
PROGRESS HAS BEEN MADE~! ^0^
Unfortunately, I lost the freaking transparency that I NEED!
What the heck!

I'm gonna cheat, and export the simgeom and use the SimCASHairSimple shader on it
If that doesn't work I am SO. Screwed.

[UPDATE]
IIIIIIIT WORRRRRRKED!

DANG! I mean what the frick! At least I can make base game accessories now, instead of always using the Supernatural necklace. PHEW; this calls for a DRINK!