The word is sitzpinkler, one that I somehow never heard before today. The Urban Dictionary defines it as "In German, the phrase for someone who sits and urinates; a 'Sitzpinkler' is equivalent to wimp, wuss or pussy."
I discovered it in the context of The BEAST's list of the 50 Most Loathsome People in America, 2006, a hilarious must-read (hat tip to Eric Zorn for the link). Person number 42 is Joe Lieberman, aka the crybaby who couldn't accept that he lost the Democratic primary and ran as an independent in the general election. The BEAST says, "For a brief, shining moment in ‘06, it looked like the nation might finally be rid of this sniveling sitzpinkler, but Joe Lieberman just keeps coming back, like herpes."
I actually know of a literal sitzpinkler, courtesy of my wife. In fact, it was her ex-boyfriend, a druggie Loser (note the capital L). She asked me one time if I ever peed sitting down (besides while conducting other "business"). I was aghast. I mean, peeing standing up is one of my favorite things about being a man. After all, the oft-cited corrollary, writing one's name in the snow, is only useful in certain climates, but being able to avoid physical contact with nasty public toilets is a great thing everywhere -- not to mention the ease with which a guy can turn any roadside ditch into a bathroom (you women wrinkling your noses right now are just jealous).
After I unleashed my speech about the glories of peeing erect (and you know which sense of the word I mean because peeing doesn't work so well in the other sense), my wife mentioned that Loser sat down to pee. I never met the sitzpinkler because he died of a heroin overdose only weeks after I met my wife. At the time she said, "You would have liked him." Several years later I said, "Remember when you said I would have liked him? You knew I'd think he was a total @sshole." And that was before I even knew he was a sitzpinkler. I'm kind of glad he's gone for a number of reasons, foremost being that I don't have to suppress the urge to kill him myself. Unfortunately, that bastard got the last laugh -- I got stuck living with the dead sitzpinkler's cats.