"To sprout" (generally used about plants) can mean "to grow/develop (suddenly/quickly)". To sprout wings means "to (suddenly/quickly) grow wings" According to "http://idioms.thefreedictionary.com/sprout+wings" it can mean (metaphorically): 1. to die and become an angel: "I’m not ready to sprout wings yet. I’ve got a few more years." 2. to be so good as to become an angel: "The kid is not about to sprout wings, but he probably won’t get into jail"