It's a basic command almost every dog knows: "Sit." Dogs do it naturally, you just have to teach them to do it on command. Simple enough, right? Basic obedience 101! Here is the anatomy of a properly executed sit, first from the side:
And now from behind:
Well, leave it to us to come up with a debate on the topic. Brutus being Brutus, he has managed to come up with his own unique take on the position.
In obedience it is called a "sloppy sit" (Oh, to see a scoresheet without the notation "SS" on it...). Brutus sort of reminds me of an old man when he sits like this, all hunched-over looking. Here's a side view so that you can get the full effect. This is the more complicated "Foot-paw-foot-paw" version, where front & hind feet alternate.
I think they get the idea, mom... Will you knock it off with the camera?
Compare that with the even more casual "on one hip" version shown here. No complicated foot placement to worry about in this sit, just let it all hang out to the side:
Brutus isn't alone, this is a characteristic Frenchie position. If you want to get technical about it (and you know I can't pass up the chance), somewhere I read that all Frenchies have some degree of patellar luxation so this is just how sitting works best for them anatomically. Explain it however you want, it's just one more thing to put on the list of why I love my Frenchie :)