An all-you-can-eat arrangement: for a fixed price you can eat as much as you like (colloquial; similar to 'tabe-houdai').
この店は焼肉の食い放題が人気だ。
This restaurant's all-you-can-eat yakiniku is popular.
食い放題で元を取ろうと食べ過ぎてしまった。
I ate too much trying to get my money's worth at the all‑you‑can‑eat.
学生は食い放題のクーポンをよく使う。
Students often use coupons for all‑you‑can‑eat deals.