Sorry, wrong bowl
The second episode of season 8. The Powerpuff girls find a real pony in Bubbles cereal bowl and scares them.
The Powerpuff girls are first seen eating their cereal bowls. Bubbles feels something squishy in her bowl. She puts her hand in it and says she feels skin. Buttercup thinks shes crazy and keeps on watching her favorite show. Blossom thinks her imagination is going a little to wild and gives her a weird look. Bubbles closes her eyes to relax when a pony suddently jumps out of her cereal. Bubbles screams, Buttercup is silent, and Blossom accidentally spills her cereal on her pants looking like she went to the bathroom. Bubbles, Buttercup, and Blossom zoom over to the Professor telling him about the pony. Professor looks down at Blossoms pants and asks her if she had a accident. Blossom stammers that her cereal bowl fell on her pants when she was scared of the pony. Professor went over to the kitchen to see if the pony is anywhere but there isn`t. Professor gives Blossom a funny look and tells her to go change. Blossom blushes and goes upstairs. Later in the afternoon the Powerpuff girls are eating lunch. Bubbles was going to take a sip of her soup when the pony popped out of her bowl and she accidentally spilled it on her pants. They all told the Professor when the Professor noticed Bubbles pants and told her to change. The samething happened to buttercup when they were eating dinner. The Girls said they were going to end it. The pony popped out again the next morning. They got a roll of newspaper and bonked it on the head. That was the last they ever saw the pony.