noun
drumming on one's belly; having one's fill
Literally 'belly drum'; refers to the act of patting one's full stomach like a drum after eating, or the state of being full. Often used in the phrase 腹鼓を打つ (to drum on one's belly).
満腹で思わず腹鼓を打った。
I was so full I unconsciously drummed on my belly.
食後、彼は腹鼓を打ちながら満足そうに笑った。
After the meal, he smiled contentedly while drumming on his belly.