For me, I'd probably first invite you to my house to go swimming in a "basement swimming pool. We'd go to the basement, where I'd tie your legs together and bring out a tube, connected to a faucet. Then the fun begins; Up the arse the tube goes, and I turn on the faucet. Cold water runs through the tube, rushing up your intestines to the abdomen. Your belly begins to slowly but surely stretch outwards. After a few minutes, your breasts also begin to grow. You've only been growing for about 15 minutes, but with the size of your breasts and belly, it'd seemed like hours. You can barely bring your arms around the two huge spherical spheres in front of you, much less the bigger one below them.
Soon, you've been there for about half an hour, and the water finally stops. But it wasn't the end. Soon, in place of the water, air flows through the tube, causing a bubbling sensation. The gurgling noises accompanied the even further distension of your breasts and stomach. Creaking noises began echoing around the room. It's become painful. You scream for me to stop. "Why?" I'll ask, "You're nowhere near full!" The air continues to fill you, and it began making room in your stomach for even more. It'd been a full hour since the air began filling you, but now the water returns to fill out what remained. As you attempt to move, all you hear is a loud sloshing and creaking as the enormous, almost perfectly round orbs that were your breasts and belly. Tight as an over-inflated weather balloon, the harsh pain you were in told you that the only way this could end is when you POP! However, just before it would all end, the tube was removed. You couldn't move, as your now O-Cup Breasts and likely over 200 inch round belly restrained you.
I grab on your belly, shaking it around. "Don't worry, I'll take good care of you. You're mine now."
I would inflate you with air into an hourglass shape and then fill you with water so you won't fly away. It would definitely be somewhere private like a house.