Cops talking about Fentanyl are like Stanley Goodspeed in The Rock talking about "VX Gas."

Your muscles freeze, you can't breathe, you spasm so hard you break your own back and spit your guts out. But that's after your skin melts off.

VX nerve agent isn't a gas, and it won't melt your skin off or make you spit your guts out or break your back, although the rest is accurate. You'll spasm and suffocate.