“Hot cakes” is an American idiom, representing a commodity that’s popular and easy to sell.
To save the day means to prevent sth. bad from happening or to prevent sth. bad from getting even worse.
A willingness to meet with your opponent half way simply means that you're very willing to negotiate and make compromises.
If someone's proposal is deemed a nonstarter, it is not very good.
If someone's words step on our toes, they can hurt our feelings real bad.
Crying wolf has become synonymous with anyone raising a false alarm, especially to attract attention.
公交充值卡应该表达为prepaid (IC) card 或者public transport card或者smart card，手机充值卡可以表达为top-up card/calling card。
Lady Luck stands for good fortune, the chance of something good happening to you.
If you have to break your piggy bank to buy something, then it is perhaps too expensive.