I've never understood that, it's so weird. People say it's because he wears lifts and I don't doubt he does, and women wearing heels do stick out their butt but they also arch their back to keep their balance. Which lifts the boobs, another plus, but it's mostly for balance. (Source: am woman, have tested the different effects of 4" heels and 4" platforms with a 2" rise toe-to-heel)

Maybe he's trained himself to "not stand like a girl in heels" and thinks he's getting away with it? Or maybe his back is unable to arch? The belly weight is the opposite of a counterbalance so that's not it. Could his cankles be incredibly strong shin muscles? No, Michael Jackson had skinny ankles.

It's a mystery, Scoob!

Edit, new theory: Diaper as counterweight