Naruto Episode 87: Keep on Training: Pop Goes the Water Balloon!
Episode 87 of 220 of Naruto, aired June 9, 2004, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Jiraiya gives Naruto the task of rotating the water in a balloon until it pops. Naruto is confident that he will accomplish this stage of the training by night, but soon learns it's not as easy as expected.