I'll tell you why I don't
Want to know where you are;
I got a joke I been dying to tell you;
A silent kid is looking down the barrel;
To make the noise that I kept so quiet;
I kept it from you, Pitseleh.
-- Pitseleh by Elliott Smith, of the album XO.
Pitseleh is a Yiddish term of endearment -- mostly. The Yiddish word Pitsl or Pitsel means 'small', although it is more often translated as 'wee'. In Yiddish the primary diminutive is -eleh (or -leh) in the singular; the longer version of the suffix (-eleh) sounds more affectionate and is usually used with proper names and terms of endearment.
Thus, the construction pitseleh literally means something like "little small one". This is usually used to refer to babies, although it can be used to simply mean a small thing, particularly a cute small thing.
The internet informs us in no uncertain terms that it is also used for a small penis. I would assume that this is a common euphemism/insult, but not the primary use of the term. YMMV.