noun-modifying (irregular)
smooth and flat; slender and flat-chested
Slang, often vulgar, describing a body type that is both smooth-skinned and flat-chested, typically referring to a prepubescent or young-looking girl. Combines つるつる (smooth) and ぺったんこ (flat).
あのキャラはつるぺたで人気がある。
That character is popular for being slender and flat-chested.
つるぺた体型を気にしている子もいる。
Some girls are self-conscious about having a slender, flat-chested figure.