Colon cancer survivor here. They’ll give you a kind of sedation where you’ll remember nothing when it’s done. The worst part is absolutely the prep to clean out your colon. It’s terrible, I know, but it’s the only way for your doctor to get a good look at your colon and then remove any polyps they find. There are other screening methods, but none of them can actually help prevent colon cancer because they’re not removing any polyps.