The squishing and smooshing of Mary's womb pressed in on Phil from all sides as despite his new form, her remained firmly lodged in her womb.
"Now now dear, settle down. Momma'll let you out when she's good and ready..."
'Oh sheesh, she's really getting into it' Phil thought as he suddenly realized how much she was enjoying this, as with each movement of his thick hooves she moaned in pleasure, her whole body shaking around Phil. He tried to stay still, hearing only the squeaking of rubber and the pressure being exerted on his new balloon body.
"Awwwww...you're no fun. Time to come out!"
Phil felt an extreme pressure as he shot out of Mary's pussy with a loud pop!, the fat baby hippo balloon tumbling into a wall with a dull thud.
"Mary! Wait! Ya gotta turn me back!" Phil pleaded squakily as Mary picked the balloon up gently in her arms, hugging him tightly before she pressed his head into her breast muffling his cries as his maw was forced around her nipple.
"Ssshhhh...there there, my baby." Mary cooed as she rocked and stroked Phil. "Now drink up!"
Just then Phil felt a trickle of liquid in his mouth, but before long trickle turned to flood as he tried to gulp down the milk as fast as he could. The sloshing liquid spilled first to his feet, filling him up to his belly in warm mother's milk. Being filled seemed to have a soporific effect on the hippo, Phil beginning to doze off as he continued to be filled.
Mary stroked the smaller hippo, knowing that as long as he was filled with her milk he'd be under her control. For now she'd let him sleep and let him adjust to his new form - he's had a big day and all. But tommorrow, maybe she'd send him out and see what kind of effect her milk would have on other humans...