Get a douch and flush your ass out. If you do it not long after you've had a shit, you can go for a good hour without anything other than ass lube and cum coming out your ass. If your "works" are a bit upset, then I wouldn't bother or you'll get in a right old mess.
You definitely DON'T want to do it right after you shit. If you take a good dump either the night before, or early the morning of, and you get buttsexed that night... you should be alright. And if it's yr ass, it's an enema, not a douche. Completely different things, completely different solutions. Douches are vinegar, enemas are saline. God only knows how buttsecks turns out with you.
different country, different meanings, a douch here is just a bulb and tube so to speak. You fill it with what you like. Seeing as I take a dump 2 or 3 times a day your theory wouldn't work, but then everybody is different I suppose. Its worked for me for many years......