Create a humorous metaphor:
One of the metaphor's most useful aspects is its ability to convey humor. Choose an aspect of your story or your character that would be most likely to be exaggerated into a caricature. Write a metaphor about it in a funny fashion.
Example: (Only highlight the text to read if you need to be inspired.)
I have a character who is very proud and snobbish, so I want to make those traits into a caricature.
She was as graceful and elegant in her movement as she was proud and snobbish in her speech: When she talked, her voice was the sound of a trumpet: it sounded like it could have been lovely if the player knew how to play Taps instead of blatting out Mary had a Little Lamb.