Able to do absolutely nothing. Therefor will do nothing but is pretty cute. The kind of teammate you wouldn't want in any FPS game. If you tyrin' to win that is. Otherwise the wuestengoldmull is always good for a dick joke or other kinds of funny nonsense.
Whilst originally describing the process of making a knot during sausage production it now has the meaning of tieing ones own penis into a knot to prevent urin from leaking out if there should be no toilet available. It is used as a sarcastic mean to brighten the mood if one member of the friend group is unable to find a toilet. Instead of doing the obvious and telling him to seek a toilet or oppotunity to pee elsewhere the friends give him the advice to perform a "Wurstknoten". The for english speakers unknown nature of the word is used to create confusion.
"No toilets? Well, seems like you gotta make a Wurstknoten."
"Had to pee but then I made a Wurstknoten, I should be fine for at least another hour"
I don't buy the schmegegge about Morty sleeping with Moira.
His version of the story was pure schmegegge.
The whole schmegegge was made up to get Liz a little bit of attention.