cheap, worthless / vile (morally low)

(formal) at a very low price, cheaply, for next to nothing

if you behave kindly towards a bad person, they will be mean; conversely, if you behave spitefully, they will be kind to you

Ellipsis of oignez vilain, il vous poindra ; poignez vilain, il vous oindra.

it will end in tears! stop fooling around! stop roughhousing! you'll poke an eye out! it's all fun and games till someone gets hurt! it's all fun and games until someone loses an eye! (used to admonish children who are bickering and fighting) / naughty! (used with sexual overtones)

curiosity killed the cat

plural of vilain petit canard

ugly duckling

Ille-et-Vilaine (a department of Brittany, France)

villain / peasant / country dweller