It's funny because biologically speaking, we are supposed to squat to poop. Back when humans began pooping, toilets didn't exist, and sitting at that angle, like in a chair, actually makes it harder on our bodies to poop. The best way is to have a small foot stool (haha stool) under your feet to raise your knees up while you blast your dookie.
These are popular signs in Turkey because there used to be (and still are) toilets in the ground where you put your feet on either side of a hole, squat, and do your business. Many people arent used to the sitting type of toilets, and they try to use them by standing and squatting. I laugh every time I go to a shopping center and see this kind of sign behind the stall door.
I'm just imagining the first time that happened to a human, and they were like what the crap?