Tā de dùpí ròuróngróng de, yī niē jiùshì yìshǒu ruǎnròu.
His belly was soft and squishy - one pinch and you'd get a handful of soft flesh.
Tips
usage
茸茸 suggests something soft and unfirm (also used for downy fuzz). Together with 肉, it's flesh that has lost its tone. Different from 肉乎乎 (plump and cute) or 肉囊囊 (slack/sagging).