YSK: If you're stuck in a "pay it forward" situation and for whatever reason you don't want to pay for the next order, you can either offer to pay the price of your order, or just say no.
from /r/YouShouldKnow
YSK: 「ペイ・イット・フォワード」の状況に陥り、何らかの理由で次の注文の代金を支払いたくない場合は、注文の代金を支払うことを申し出るか、あるいは断ることもできます。