"Jerking my Chain"

Surely it has the same origin as the
British "Pulling my chain", from lavatorial
origins. Is yanking the same as jerking anyway?

Depends on what your doing. :) But very similar, yes. Perhaps Yanking is an Americanization (Yankees).

I've alway heard that this phrase came from jerking a dog's chain which is very disturbing to the dog. Jerking someone's chain is doing something to purposely upset them. I don't see what plumbing has to do with it.
ES