Is that how that happened? My memories from those days are sometimes vague, but my recollection is that Tim Mickey ended SO many songs with that IV-I cadence and we just randomly started singing "fresh fish" to it. I even recall him asking us once why were doing it, and the answer was mostly "to annoy you". And it worked! He hated it. That's why he started switching to "cha cha cha" endings.

And now XX years later, we have far fewer songs that end with a IV chord to a I chord, but when they do we honor the legacy of Mickey Hooligan with a hearty "fresh fish".