Opioid RC that makes you tired.

I found something on the street that was supposed to be F but it’s not. It either makes you nod out or nothing. If you have euphoria, you can’t stay awake. It’s the weirdest thing I’ve ever seen. But it’s potent. What rcs are like that where you just can’t resist falling asleep on the stuff if taking any kind of active amount

That sounds super sketchy, It’s probably some really potent RC or can be synthetic opioid. Could be SPB or something similar.