Why not just keep using "ichirinsha" then? Once the terminology's been explained, there's no reason you can't keep using it to maintain the joke, rather than switching back to more standard terms.
In fact, for this one, the joke doesn't rely on the actual meaning at all, just in the way it sounds. I'd say that makes using the original term more viable.
It rather goes against my usual policy for translating, but I'll give it a shot (though Danbooru's a bit laggy right now). I generally try not to have a translated joke rely on understanding the original language, or else, what's the point of translating?
Back when they sold TMNT action figures, each package had a number of "pizza points" printed on the box. I cut them out and saved them, but there was no indication as to what they were for.
Reminds me of the days when I'd collect Kool-Aid points for stuff. I only ever got enough to get a troll doll in bright pink shorts, but it felt like an accomplishment.
Fluffy!Tr-The Dragon Lord has declared that if one collects many of them, one may trade them for such things as an ichirinsha! Kept in Japanese for the sake of the gag, it means "unicycle" or "one-wheeled cart". It could also be interpreted as "Ichirin cart".Do whatever you want..... What am I to do with this trash?Too close!So, is that?Eh?Eldest Daughter! I have collected bell marks on your behalf....this kind of...So I'm asking, what can you do with them?!How cruel of you to call them trash! After all the trouble I went through, night after night, steadily continuing to clip them out with scissors and collect them...Well, if it's called an ichirinsha, then......it must be this kind of...Oh, I see.I'm tired of this...Ah, um, that is, is it all right if I use these bell marks myself after all...?...so, what's an ichirinsha?SqueeezePlease redeem them!Imaginnne...LOOOMM