Is it possible to induce a trip ( like an acid trip ) without doing any drugs or anything illegal?

The only thing that comes to mind is a state we used to call FLASH BACKS. In the 1970s when acid was acid and a trip was like a holiday a lot of people said that weeks and even months after their initial trip -they would have the sensation exactly like they had when they were peaking. Probably doesn't answer your question because it takes a drug to begin the reaction. Cheers

Absolutely. I do it all the time. I meditate and have a wild trip. I imagine what it was like in my past life and get myself into a meditative state. I close my eyes and let the imagination run wild. I have a very over active imagination. I don't need drugs or even a tv set.

Try not eating or drinking for a week and then spinning round in a circle till you fall over