“Give someone a run for his money” 源自赛马这项活动，那时侯的规例是，如果一匹马要参加比赛，就必须要有人在它身上下注，也就是说，没人下注的马就不能参加比赛。当一个人下注在某匹马身上，表示他想这匹马为他跑一场“a run for his money”。
后来，”Give someone a run for his money” 演变成让他受到挑战、不会让他赢得那么轻松的意思。比如A很会打网球，B虽然没有A打得厉害，可是他们的技术相差没有很多，这时候你可以说“B gives A a run for his money.”
(1) Martha won the tennis competition at our school last year, but this year I'll give her a run for her money!
A: Let's play a game of chess. I know I will win though.
B: Don't be so sure! I'll give you a run for your money.
A: Judy is getting pretty good at badminton. We played yesterday and I beat her, but she really gave me a run for my money.
B: Yes, she's been practicing really hard lately.