Is the word チェリーボーイ (Eng. "cherry boy", meaning "male virgin") a genuine loanword from English, or is it wasei-eigo?
I would have thought it to be a genuine loanword, but the sources cited on English.SE here seem to indicate that the word was in use in Japan by the end of WWII (c. 1945), but is only attested in English back to the 1970s. This suggests that "cherry boy" might actually be a "reverse" loan of the wasei-eigo back into English, kind of like "salaryman" and "office lady". The relative frequency of these words (incredibly low in English; somewhat higher in Japanese) also sort of points in this direction.
語源由来辞典 says 『「チェリーボーイ」は和製英語と思われがちだが、アメリカでも用いることはある』, but the mere fact that the word is used in English does not necessarily indicate that it isn't wasei-eigo (again, like "salaryman").