Every language has colourful sayings that don't translate well into English.
Post them here for fun and profit*.

Here are some sayings from Belgium/the Netherlands:
  • To polish the plate: To run away
  • To send you cat: Not showing up at an appointment
  • Now the monkey comes out of the sleeve: Now the truth is uncovered
  • Better one bird in hand than ten in the sky: Something is better than nothing
  • Looking for nails at low tide: To nag about details
  • When the cat's away from home, the mice dance on the table: If left unsupervised, people will take advantage of any situation
  • I haven't eaten this (kind of) cheese: I don't understand this subject
  • To call a cat a cat: To say it like it is
  • To turn a mosquito into an elephant: To exaggerate
  • A storm in a glass of water/a fart in a bottle: Making a lot of drama about a small issue

I'll probably think of more later on, but I'm curious to hear about sayings in other languages as well

*not really for profit