What Pincus fabricated.

(Just a heads-up: this joke I once heard deals with religious sects and has a vulgar punchline.)
Two Hassidic Jews in the Castle Hill district were complaining to their tailor, Pincus, about the hue of their suits.  "Pincus," said one, "the last suits you made up for us just weren't of a black enough cloth to define our faith.  What we need is the blackest, darkest cloth a mensch can possibly come up with."
So Pincus presented them with a certain kind of cloth and said, "See how black this cloth here is in color?  This is the kind of cloth nuns use in their habits.  There ain't no blacker cloth."
So the two Hassidic men agreed, and had Pincus make up two fresh suits of that very black cloth for them for a specific price out of their budget.  Later, those two men were walking the New York street, feeling somewhat confident in their new, black suits, but also a bit curious about them.  And it was soon that they spied a pair of nuns walking the other way from nearby a local convent.  Needless to say, these two Jews' curiosity was piqued, and one of them stopped to measure the blackness of the new cloth against the nuns' habits.
After they had moved on, the one of the nuns against whom he hadn't measured was a bit confused.  She asked her friend, "What was that about?"
"I don't know," said the other nun.  "That gentleman just held his sleeve against my habit, said some Latin phrase to his friend and walked away."
"What Latin phrase was that?"
"I think it was, 'Pincus fuctus.'"