Yes, it was.
in reply to a message by Fiammetta
Yes, it was (or maybe it still is) a slang term for that. I only know that because one of my sisters used to be into fan fiction. (Note: She never wrote or read 'lemon' fan fiction. She learned what the term stood for before she read anything like that, thank goodness. We would have had a really angry mother if she had read or written something 'lemon')