Yes, but I can't for the life of me remember what number it is. It's the episode where Kururu was going to be leader for the day, and Keroro and Co. couldn't find him. They called Aki, since they knew Kururu has a soft spot for her (enter...this picture) and she was on a spa vacation with the kids, showing them a free pass that Kururu had given her.
If you go on wikipedia, and look up "List of Sgt. Frog episodes" you should be able to find it in one of the middle or later seasons. The title of it is something like: "Kururu: Leader for a day".
I may be able to find it for you, but I feel too lazy and tired right now, honestly. ^_^