I think it comes from here: “An anime/manga based fan-work that depicts sexual …

• Tags: Crossover, Image Gallery, JC Staff, Louise, Nuns, Tsundere, Zero no Tsukaima
  

Comment on A Certain Zero no Tsukaima F Anime… by Lunatique:

I think it comes from here:

“An anime/manga based fan-work that depicts sexual acts.

Often shortened to simply “Lemon”, the term is actually derived from a hentai anime in 1984, “Cream Lemon”, which told a story about a girl called Ami and her relationships.

Since then “Lemon” has been used to refer to all sexually-oriented fanworks, in particular fan-fiction.”

I guess this is why Haruhi’s DVDs covers have a Lemon on it.

If I am right there is something about Melon and others fruits too.

Lunatique made other comments on this post:

• A Certain Zero no Tsukaima F Anime…:
  

  It’s not Louise, it’s Lemon-chan!

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