他帮了你一个不小的忙，你说要请客，他摆手说「举手之劳」。这句话的功能是？
They did you a real favour; you offer to treat them and they wave it off with 举手之劳 (“it was nothing”).
全球翻车率（内测预估）
A这忙确实毫不费力
zhè máng què shí háo bú fèi lì · the favour really did take no effort
B暗示他不想再帮第二次
àn shì tā bù xiǎng zài bāng dì èr cì · hinting they won't help again
✓把人情说轻，好让你不必觉得欠他
bǎ rén qíng shuō qīng，hǎo ràng nǐ bú bì jué de qiàn tā · downplaying the favour so you don't feel indebted
D嫌你请得不够诚意
xián nǐ qǐng dé bú gòu chéng yì · they think your treat wasn't sincere enough
「举手之劳」说的从来不是这件事有多轻，是他愿意让你觉得有多轻。
举手之劳 (“just a lift of the hand”) isn't a description of the effort. It's a gift: they're shrinking the favour so you don't have to feel indebted.