Hate it when it happens

How on earth do you do that?

You practice. Masturbate until you almost come, keep pushing it off. Then learn to not relax the bit that makes you ejaculate, while relaxing and enjoying your orgasm. I'm not saying it's easy and there are probably other methods.

Okay, but is this a healthy thing to do? Do you now control when you actually cum or you never cum again?

I cum when I choose to, I can't do it on command or anything but I usually save it for last when everyone is exhausted.