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：如果你陷入了 "支付寶 "的境地，不管出於什麼原因，你不想爲下一個訂單付錢，你可以提出支付訂單的價格，或者直接說不。