DS1 (2.11) does it constantly. Generally his toys, when they're spread across the floor. He seems to do it absentmindedly, just because things are under his feet.
We say "don't do that, it might break" - and I do get that that isn't totally helpful, because most of the time they DON'T break so he doesn't see that consequence as real.
He's an incredibly good kid but just cannot seem to resist this urge to explore things with his feet. And when I tell him off for it he gives me that hurt and bewildered look that suggests he's not being deliberately naughty, but instead there's something going on that I just don't understand.
So - is it a developmental thing or something? I'd obviously much rather he didn't do it - but if it's an actual Thing, rather than just him being a bit contrary, I'll have a lot more patience with it (especially if there is some explanation that might help me figure out how to stop him doing it!).