The catchy song at the top of the post is from a Bollywood movie about all the western hippies who kept coming to India to learn about Hinduism (etc.) but also kept encouraging local young people to take drugs and have orgies, leading to a moral panic.
At one point in history, backmasking turned into a very popular conspiracy theory. This site lets you play suspected backmasks forwards and backwards, and you try to guess what satanic message they're supposed to encode. Once you read the conspiracy message, you can't hear anything else.
The original Bushmiller run of Nancy was probably the greatest newspaper comic strip ever made. A lot of people at the time recognized this and wrote long analyses where they begrudgingly admitted to loving a comic they hate, and praised Bushmiller while saying things like he was too much of a sub-human idiot to understand his own genius. Here is one of the better and more interesting examples of that genre.