how not to use metaphors   (link)

http://www.schoolzone.co.uk/students/exams/metaphor.htm
"His thoughts tumbled in his head, making and breaking alliances like underpants in a tumble dryer."
"He was as lame as a duck. Not the metaphorical lame duck either, but real duck that was actually lame. Maybe from stepping on a land mine or something."
google bait: "don't drink petals"