Exchange
Reciprocation
noun, verbal noun
おうしゅう
応酬 （おうしゅう） Exchange, Reciprocation
報酬 （ほうしゅう） Reward, Compensation
Reciprocation 応酬 is a response 応 repayment 酬
Oh おう shoot しゅう, I forgot to give something back in Exchange.
Oh おう shoot しゅう, I forgot to Reciprocate.