The sheer fact that all the protagonist Yoshis are newborns, and brave levels and dangers that would make their elders proud.
The way players find out that bosses exist in the game: they eat the required amount of fruit to end the level, but the screen doesn't fade away like normal. Instead the screen breaks up into fragments that fall away and reveal a new stage that the boss makes their entrance in. Counts partly as an Oh, Crap! moment and partly an awesome moment.
