There are descendants of the renown Hasidic rebbe, R' Levi Yitzchak of Berditchev with the surname Derbaremdiker (דערבארעמדיקער) which means "the Merciful One" in Yiddish and refers to Hashem. I once heard a story concerning the origins of this obscure surname, which goes like this:
It was during the time that the Polish government was forcing the Jews to take on surnames. R' Levi Yitzchak of Berditchev was in his beis medrash davening when the government officials came in to talk to him and record which surname he wanted. But the Rebbe was so engrossed in his tefillos he was murmuring over and over again "Derbaremdiker, Derbaremdiker..." ("The Merciful One, the Merciful One...") and wouldn't respond to the officials so they recorded "Derbaremdiker" as his surname, assuming this is what he wanted.
What is the source for this story, and what year did it circulate? It sounds nice but maybe a bit far-fetched; like someone made it up to understand why they had the surname Derbaremdiker and knew R' Levi Yitzchak was in their yichus.