A friend bought a 300 dollar bottle of absinthe once, and I really wanted to see the green fairy (or, you know, just catch visions or something), so I got past the fact that I don't like licorice (it reminded me a lot of sambuca), and guzzled a bunch.
Nothing happened for a while. I wasn't super disappointed, as I was feeling it like a regular alcohol drunk, but it wasn't anything I couldn't have gotten off of my preferred drinking choices.
About an hour after drinking the first few glasses, lightning started to dance around everthing's edges, kinda like a bad fake 3D effect from the red/blue glasses. Interesting, but ultimately kind of sickening. I tried not to think about it and just had fun... for a while.
Then I apologized tearfully to a cat for everything we had done to it's people since just before the rise of Egypt.
We didn't have a cat.
Never tried it again.
EDIT: Just looked up Absinthe on Wikipedia, and it says that the hallucinogenic effects have been exaggerated... I don't know what to tell you, this is what happened to me, believe it or not, I guess.
I mean, I might have had some other drugs that evening, but I can't really recall. Certainly don't remember specifically taking anything else, beyond alcohol- just remember being hyped to try Absinthe.