It's not placebo. I've experienced it many times. But there is a genuine difference in how people treat you on the same day after you jack off. It happens with everyone, family or stranger. They treat you a lot worse and you're more likely to get in a argument or have something go wrong in anything you are doing. A couple of weeks ago, when I jacked off 5 times on the same day, I got into a bad argument with my dad and we didn't end up talking for an entire day. It only got better after 2 days after I stopped.
Immune system weakening is because you lose a lot of vitamin C, minerals and nutrients after every orgasm. Right after I jacked off for the 3rd time today, I started getting a bunch of bumps on my skin but they went away after a few hours.