I regularly infect other peoples Laptops, and my own VMs as well, with a very common Spyware/Adware/Trojan. It comes in two different versions, the newer one being much more aggressive than the older one. It's a 'premium' product costing up to $250 officially. The only way to really get rid of it is a full disk clean, otherwise it hides itself into separate, hidden partitions. It IS very annoying to install, considering it's very slow, buggy and needs a terminal to circumvent the online account (even more tracking, technically, but I don't want to create an account myself). And it even crashes all the time, takes ages to update and is a magnet for other viruses. I myself of course don't have it, i use Linux after all. But most people seem to like Windows, for some reason, so I have to install it for them.