to stuff one's cheeks; to fill one's mouth (with food)
一口で大きなおにぎりを頬張った。
I stuffed a large rice ball into my mouth in one go.
子どもがケーキを頬張っているのがかわいい。
It is cute to see a child stuffing cake into their cheeks.
彼は食べる速さが速く、いつも大口で食事を頬張る。
He eats fast and always stuffs food into his mouth in big bites.