Isla Esme
Depicting idioms literally!
Examples:
  • Raining cats and dogs
  • Bite the bullet
  • Once in a blue moon
  • Piece of cake
  • Let the cat out of the bag
  • Burn midnight oil
I think it'd be fun to have stamps that depict a picture of the above and to send it to pen pals whenever they're in a similar situation. For example, for wet weather, I can send a raining cats and dogs stamp and for my pen pals who are studying for their exams, I can send a stamp on burning midnight oil.