Alas, I don’t have a reference connecting both. I can, however, tell you that “bum”, according to R.A. Spears’ Slang and Euphemism, is defined as
bad. The opposide of “rum,” meaning “good.”
Technically, it could be applied to anything that merits the “bad” label.
“Gouge” can also mean “to cheat.” And the beauty of this term is that it can be used either way; i.e., to cheat at something or to cheat someone. So, whether one is cheating on a Latin exam or cheating someone out of his/her money will depend on the context.