I have a certain tattoo on my arm that always leads people to ask me about it, so I have my usual response:
"It's almost ineffable really, but I can try. You essentially have to ingest the molecule one way or another, I do it by vaporization with a water pipe. Within a few seconds of holding in the vapor, a high pitched tone envelops my reality. My perception 'wanes,' and an intense high rushes over me. I forget what I am doing except I know that I must close my eyes.
I lay back in a comfortable position. I already made sure that my friends and environment will be silent. Within my mind I enter into massive fields of color that all take on different shapes. I may feel as if my body is again enveloped in these fields. Impossible geometries, insane colors, and I sink deeper into the realm.
As time passes I may meet with various freestanding figures who I call entities. I have various interactions with them. Generally as the trip starts to end, I get a huge smile across my face and the thought 'I should ask my friends to let me take another hit' comes into my head. It's funny because it's already been a whole 5 minutes.
The craziest part is the integration. I forget much of the specifics of what I experienced, but as months go by memories come back to my head, and I realize new things about my life, knowledge, and certain fields. It's intensely powerful, and although completely alien, staggeringly human at the same time."
If I give them the whole spiel they generally smile and nod, but I can tell they're thinking, "This guy is crazy, but whatever floats his boat."