Finnegan pin n. a non-existent part or tool; a thing whose name is forgotten or unknown; a doo-dad or thingamajig. (source: Double-Tongued Dictionary)
Further reading
Daniel in Nicholasville, Kentucky, says his grandfather would warn that if he got in trouble, he’d be in deep yogurt. That’s probably just a euphemism for deep doo-doo, deep foo-foo, or an even stronger epithet piled high. This is part...
Nikki in Northampton, Massachusetts, wonders about a term her dad used for someone who’s a little odd or weird: do funny. As far back as the 1850s, Do funny or Doo funny was an amusing last name for characters in satire, whether in newspapers...