1. “cute as a kitten,” comparing the way someone looks to the way a kitten looks. 
2. “as busy as a bee” comparing someone’s level of energy to a fast-flying bee.
3. "as agile as a monkey" implying someone can move as well as a monkey does.
4. "as snug as a bug in a rug" comparing someone who is very cozy to how comfortable a bug can be in a rug
5. as happy as a clam" comparing someone's happiness to the contentment of a clam.