Stacy Keibler -- Does It Look Like There's a Baby In Here?

George Clooney's GF Stacy Keibler just proved there IS something inside her belly ... six pack abs!

While rumors have been going wild over whether Stacy has a baby bump or not, the 32-year-old just tweeted a pic of her sweaty, gorgeous, ripped, flat stomach during a workout in Italy on Wednesday.

Besides the toned tummy proof, sources close to Keibler are scoffing at the suggestion she's with child ... telling TMZ the rumors are "100% false."