noun
Used when two parties are even, especially after settling a debt, score, or mutual favor. Often in the phrase おあいこにする (to call it even).
これでおあいこにしよう。
Let's call it even with this.
おごってもらったから、今度は私がおごっておあいこだ。
You treated me last time, so now I'll treat you and we'll be even.