Verb-1. To defecate. Can also be shortened to "dimes". 2. The need to defecate in a hurry. Usually there is a small window from when this phrase is uttered to the act of defecating.
Mark-"I really need to drop dimes!"
Anne-"Don't worry, I'm pulling into the nearest rest area."
Mark-"I hope it's close...dimes, honey, dimes!"