It's funny how, whenever the topic of absinthe comes up, you'll get a stream of people talking about how they had absinthe once in some back-alley bar in the Czech Republic and got high off their rocker.

There is very little evidence that thujone has any hallucinogenic effects. It acts on GABA receptors, and as such, in large doses it may cause muscle spasms, convulsions, and potentially death, if you're into that kinda thing.

The amount of thujone that is in absinthe is such that you would be well dead from alcohol poisoning before it had any of these kind of effects. I suppose you could up the wormwood content massively to increase the amount of thujone, in which case you'd probably be dead from wormwood poisoning instead. Plus, it would taste really, really bad.

What absinthe does do is get you extremely drunk very quickly. If you're expecting to get high then for one thing, that in itself can have a placebo effect on your perception, and for another, it's very easy to attribute the effects of alcohol to the magical green fairy dust.