He found a waterfall, he wraps his tail up around a tree and opens his maw and gulps down a thousand gallons of water. As this happens, his belly starts to expand very large, then gets extremely huge he starts leaning over, but thankfully, his tail is wrapped around the tree. He puts his hands on his belly and starts rubbing it as he continues drinking. He finally stops and smiles as he is hydrated and full

Black Dragon: slurps the lips I love my big/huge belly.