Riddle: Now matter what, I come to you round, Floating up, floating down, A single pop, I'm on the ground, Then comes your unpleasant frown. What am I?
Answer: I am a bubble. Bubbles always come out round no matter how you blow it. Bubbles also pop when they touch the ground. Usually bubbles go up and then down. Most of the time you and I will frown when a bubble pops. Therefore, the answer is a bubble.