Ive come across this nasty stuff in the states.

Two causes.

Anaroebic bacteria overgrowth on the weed (mold). Weed that has gotten wet.

or

Weed contaminated with the meth chemical, anhydrous ammonia. Same containers, purposeful contamination etc.

From what I keep hearing this is happening too often in many places in the States.

If it smells like cat piss, human piss or ammonia avoid smoking it.