To make plans based on future events that might not happen. A shortened form of the phrase "count your chickens before they're hatched." Often used in the negative. When my mom heard that I was preparing my campaign before even being nominated, she warned me, "Don't count your chickens before they're hatched." Why are you begging to drive my car to school tomorrow when you still need to take your license test in the morning? Don't count your chickens, babe!