Pre-Warn them they are about to get offended
The act of telling someone what is going to happen to them will automatically trigger that persons’ defensive mechanism. Humans naturally want to believe that they control every aspect of their destiny so to even suggest that you know something that they don’t will make them want to challenge whatever information you have, in this case them becoming offended by your future comments.
I’ve found that on average most people will protest claiming that they’ve had horrible experiences in the past and then give you examples of times in their youth when something incredibly offensive happened to them yet they weren’t offended.
Now they have given you the keys to be as brutally honest with that person without fear of reprisal. Make sure to maintain constant eye contact and watch for subtle body language like a twitch in the eye, grab of the arm, folding of arms, eye scratching, etc. This is a good way to tell if you’re actually striking a nerve.
They might pretend they aren’t offended but this doesn’t mean they aren’t lying to you. Chances are they are offended but they can’t show it because of their previous statements about how they never get offended.
Be warned if you use this tactic recklessly and around the same individuals they will harbor a deep resentment towards you. One day their levies will break and you’ll have to deal with the full fury of their concentrated anger.
How to counter this tactic
If anyone ever tries to use this move on you and you want to avoid it, when they say the magic words “you’re probably going to get offended…” simply reply “yes, you’re probably right.” and cease communication or change the subject. You already know what they’re trying to do and unless you feel like playing the game you can jump in but if not just shoot em down early and save yourself the trouble.