Apparently, it's a long-standing tradition handed down orally that the Roman soldier who raped Mary was called Panderik. So I've been told. Caveat Emptor. 

Yoshke is a diminutive of J.

For an online source see the bottom of [this page][1] which claims:

>  Yoshke Panderik (יאָשקע פּאַנדריק) or Yoshke Pandre (יאָשקע פּאַנדרע‬). A book called "Toldot Yeshua" claimed that his father was actually a Roman soldier named "Pandeira," whose identity was hidden by Mary. See also: http://forward.com/culture/160737/yoshke-of-nazareth/

The link quoted has other ideas.
Yoshke is'n really diminutive but nomatricon (abbreviation) of Yimakh shemo יִמַּח שְׁמוֹ "May his name be obliterated" is a curse  the name of particular enemies of the Jewish people.


  [1]: http://www.jewish-languages.org/jewish-english-lexicon/words/628