The idea of censorship is millenniums old. If you think it can only happen online, then you have been spared the worst of humanity.
If you are not allowed to vent your opinion in a (real world) public marketplace with 1000 people listening to you, but you go to a forest, where only birds listen to you and you shout the same opinion, are you censored or not?
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The best ones are thoughts that many people can relate to and they find something funny or interesting in regular stuff.