>>33810327 (OP)
I'd say read a book, but that's either a really good idea or a really bad idea depending on what you read.
You could kill some time reading random or semi random wiki pages. Before the internet and computers were everywhere, when bored sitting around in libraires we'd read encyclopedias. It was a decent way to kill time and learn random stuff in the process. Really irrelevant stuff, but factual stuff. Giant encyclopedia books that were spread across like 20 giant thick books were Wikipedia before Wikipedia existed.