I found the info I was looking for on FLCL sites: it's a reference to an event in Gundam's development, and a phrase used by some Gundam fans.

This is a list of the current candidates. I was watching FLCL Episode 1, and heard the reference to Gundam clearly for the first time. Not knowing what it was, but being sure of how it related to the plot, I looked it up in wikipedia. Featured lists candidates list . At this step I ran into difficulty, as I had no solid sources, and If there is other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. The most compeling references I've found are the Urban Dictionary's Entry Gundam HammerSo I have a potentialy meaty addition to the article, but no way to reference or even truly verify it's validity. In responce to Naota claiming he dosen't know what "Fooly Cooly" is Kamon (Naota's Dad) says "That's what it is. The central characters in FLCL (also known as Fooly Cooly), a 2000 Japanese anime produced by Gainax and Production I.G, with two additional seasons released in 2018. If anyone has any suggestions for a trustworth resource, I'd be realy glad to hear it.--So, you're asking for justification? No information. Having secured this information as fact in my own mind, I returned to Wikipedia hopes of enriching it with the information I had just retrived. FLCL (pronounced Fooly Cooly, not "Eff-ell-see-ell") is the story of Naota, a young Japanese boy who lives with his father and grandfather, is the object of inappropriate attention from his brother's ex-girlfriend, and generally feels his life and town are really boring. I'd like to add some information about the reference to Gundam in the Manga-style part of this episode around minute 12. When questioned by fans he supposedly responded Gundam was "just a giant robot anime after all". Featured lists are considered to be the best lists in Wikipedia, as determined by Wikipedia's editors. Later, a weapon named the "Gundam Hammer" was introduced, suffice to say it was highly unrealistic. Image:Flcl-1.jpg is being used on this article. Originaly, Tomino claimed that Gundam was NOT "just another giant robot anime" and that is was intended to be a realistic represtation of the complex political and social impatcs of warfare and the humanity (or inhumanity) of man during times of desperation. More information was revealed about the project at Anime Expo 2017, confirming that the series will begin airing in 2018, and The Pillows, who made the music of the first series would return, ad both seasons will feature different stories.

I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. The six-episode series was released in Japan from April 2000 to March 2001. Articles are reviewed at Wikipedia:Featured list candidates for accuracy, neutrality, completeness, and style according to our featured list criteria. Note that any fair use images lacking such an explanation can be deleted one week after being tagged, as described on FLCL (フリクリ, Furi Kuri; known in North America as Fooly Cooly) is an original video animation series written by Yōji Enokido, directed by Kazuya Tsurumaki and produced by the FLCL Production Committee, which included Gainax, Production I.G, and Starchild Records. Consequently, "Gundam Hammer" passed into the gundam fan's vocabulary as a word for a newly introduced element that blatenly contradicts previously held policy. I don't want to spread heresay on wikipedia, but i'm no longer sure this popular story about the origins of "Gundam" reference is true at all. Naota's Gundam Hammer. Most of the pages I find on Google are about this scene in FLCL, and not about Gundam at all. The show revolves around Naota Nandaba,and his life after the appearance of Haruko Haruhaha, and Medical Mechanica.