Simile used to describe a person or event that acts or is outside of the norm in either a sneaky or fun way. May also be used in elliptical form (parts of the phrase are implied and not actually spoken). Origin: Homer Simpson.
"Allison likes to wear shiny pants when she's drunk; she's crazy like a fox."
"Becca is 'crazy LIKE a' today because she had 3 Frappucinos for breakfast.