Is that so? I'm not too familiar with perverted slang but yeah maybe that's the real joke
I don't know. I'm asking. I've heard it was something starting with "chi" and considering the joke seems to be related to things ending with "pen" I concluded that "chipen" must be a dirty word.
Only one thing comes to mind. Chikuwa is tubular snack often made from sugar and or mashed up fish (there's a word for it, but I can't remember), kinda like a fish cake. Chikuwa is similar in composition to satsuma-age, which is essentially a deepfried fish cake. In certain parts of Japan (particularly central Japan), locals have developed a variation of satsuma-age called "Hanpen." (Which is ABSOLUTELY AMAZING). Goya was constructed by Yokosuka Naval Arsenal, which lies just beyond the "Hanpen" region. It's a bit of a stretch, but the admiral could have been trying to bait Goya into saying "Hanpen."
This is Champaign-dechi!
ChanpenIt's Teppen-dechi!A Chikuwa.It's Hanpen-dechi!Then what is this?A badge-dechi!
WappenA mechanical pencil-dechi!
Shaapen