Was (over)thinking about 矢鱈 and 出鱈目 today and why there's a 鱈 in both words. It's ateji, and if you want a kanji for たら, it going to be 鱈. So there doesn't have to be any deeper meaning. But I still looked.
For 矢鱈, Wiktionary has this etymology:
The kanji are an example of ateji (当て字), perhaps chosen also for the random juxtaposition of 矢 (ya, “arrow”) + 鱈 (tara, “codfish”).
For 出鱈目, there's this answer:
There are few theories about its etymology, but one prominent one is that it comes from "出たら目", which approximately means サイコロを振って、出たらその目に従う i.e. "roll a dice and behave according to that".
Whether or not this theory is correct, I think it explains the nuance well. I.e. it means "To behave random", "Do something without thought", "saying something without basis that just came through one's mind" etc. Note however, that it's exclusively used for negative description.
Not very satisfying, but I can imagine yakuza cod shooting arrows at fishermen or playing dice.
Then I noticed this in the definition of 出鱈目: nonsense; irresponsible remark; codswallop; hogwash; rubbish
It never bothered me that there is a cod in codswallop or a hog in hogwash, but here we go. For codswallop:
A frequently given etymology, although widely rejected as a folk etymology, derives it from Hiram Codd, British soft drink maker of the 1870s, known for the eponymous Codd-neck bottle, with the suggestion that codswallop is a derisive term for soft drinks by beer drinkers, from Codd’s + wallop (“beer”), thus sarcastically “Codd’s beer”.
The Codd-neck bottle is still popular in Japan where it's called ラムネ. Here's a wikiHow on opening a ramune bottle.
I am definitely calling the pink plastic plunger a codswallop from now on:
This is also the name given to the wooden device placed over the neck of a codd bottle and given a push (wallop) to dislodge the marble in the neck of the bottle. The word has also been used to describe the process of opening a codd bottle.
TLDR: 玉押し) – codswallop
by japh0000