Well until the baby comes out, lol. The things I remember trying that were much harder with the constantly shifting weight distribution were roller skating and cartwheels. Bigger and bigger till the baby punches its way out of your abdomen (since in sex ed they probably didn't cover that part either).

But seriously, if women can handle that constant change in weight distribution, I am sure a guy with a massive schlong can handle having it without falling over. Unless it has a mind of its own and gets tangled around his legs or something.