Brandon T. Jackson -- Dani Mathers' Gym Pic Not Shocking ... You Have NO Privacy! (VIDEO)

Don't just blame Dani Mathers for the gym sauna pic she posted of a stranger -- without the woman's knowledge -- blame the woman too ... according to actor Brandon T. Jackson.

The "Tropic Thunder" star had a much different perspective on the case everyone's talking about -- former Playmate Mathers body shaming the woman on social media after posting the image she secretly shot.

Brandon, who is a funny guy, was NOT joking when we got him in Bev Hills. If it sounds harsh to blame the victim, check out Brandon's take -- he might have a point.

Sadly.