The crowd at Kushstock did exactly what they wanted to do -- get super stoned -- because one of the acts swapped out a simple fog machine for weed smoke that got blasted into the audience!!!

Rapper Chucky Chuck gave his fans an experience they'll never forget, though the memory might be a little foggy ... posting the vid from this weekend's festival in Adelanto, CA with a caption that says, "F*** a fog machine."

The artist says he worked with 2 custom cannabis creation companies to make the impossible possible -- building what looks like a leaf blower attached to a big pipe -- with a bunch of weed inside, of course.

It looks like the audience was loving -- and inhaling -- every second of it ... it's called Kushstock for a reason, people.

Good vibes by all ... profits at the food tents must've gone sky-high after this one!!!

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