I don't understand

[ShamikaT]

I would've posted this in the zeta forum, but someone named SHELACIOUS would've deleted it.
-brick wall- pisssssttttttt

What do they mean when they be up on that "kryptonite"? From my understanding, a crypt is some kind of space or hole. What space or hole is they referring to?

I asked here on GC, because I think that yall (unchurched black folk) would know what I'm talking about, just with anything else that has to do with hip-hop culture.