“cute as a kitten,” comparing the way someone looks to the way a kitten looks“as busy as a bee” comparing someone’s level of energy to a fast-flying bee"as snug as a bug in a rug" comparing someone who is very cozy to how comfortable a bug can be in a rug"as happy as a clam" comparing someone's happiness to the contentment of a clam"Life is like a box of chocolates, you never know what you're going to get." comparing the uncertainty of life to the uncertainty of choosing a chocolate from a box
