One of the first, if not THE first psychadelic-induced songs ever created. The studio techniques used to create the song were (and still are, actually) revolutionary for their time. Definitely worth a listen, even if you are sober (it's an even cooler song when you're buzzed!)
Can be found on The Beatles' "Revolver" album.
"Tomorrow Never Knows" is one of the greatest/coolest/technical songs I've ever heard.