I have successfully disabled the frelling nudge "feature." I have no clue why LJ thought this frelling thing was necessary, but they certainly don't make it easy. You have to go to the administrative console, type "set disable_nudge 1" (without the quotes) in the posting box, click on [execute], and Bob's not only your uncle, he can't nudge you.
If someone tries to nudge you, LJ pops up a vaguely judgemental message blaming you for ruining their nudgy fun:
While we know you want to hear from dxmachina, they have disabled nudges from other users.