Challenge
Malaphors
Smash two idioms or cliches together to get something new (Famous example: "We'll burn that bridge when we get there.") May be funny, thought-provoking, odd...
Idiom Mashup
Drastic times call for an arm and a leg.
(Nonsense to get this up to 15 words)
(Also, I'm not sure I did this right... but, whatever)