Really? It seems plumb is the tool and plum is the fruit.
Heh, "plumb fagged." That's genius.
The fluidity of language. One day's mistake is the next day's proper usage.
Haha, quite the high horse for a self-proclaimed awful speller. (At least I think that was you.)
Anyway, hopefully someone can check OED and see what's really what.
Also, for the record, plum isn't always a noun. It's also an adjective meaning "extremely desirable, rewarding, profitable, or the like:
a plum job in the foreign service." Whether that meaning derives from plumb as well, I'm not sure.
pixote