Sgt. Frog Episode 110: Keroro - Quite Possibly the Best Medicine Ever / Keroro - All Paths Lead to Star Fruits!
Episode 110 of 358 of Sgt. Frog, aired May 19, 2006, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Keroro gets terribly sick with some mysterious illness, and the only cure seems to be... starfruit? Source: crunchyroll