probably mdma but the mangaka drew a HUGE bag full of dope, which was kinda weird. The shady ojisan's intentions are unclear but since it was their first time trying "drugs" I think he gave the kids powdered ecstasy so that the dumbasses wouldn't od from taking a bunch of pills at once since the effects take a while to kick in when it's taken orally.
just read some answers here, it's definitely not cocaine.
Ecstasy was my best guess as well, but It's supposed to give you an energy boost and the characters looked drowsy. Maybe it hits different when you snort it, rather than taking it orally? Or the author doesn't know how drugs actually make you feel... The only thing the author got right was the horniness
What in the hell did they snort?