I think "bubba'd" gets taken out of context to often. For example, if you put a Tapco T-6 stock on a SKS and did not make a single permanent modification, then it's not bubba'd it's altered in a manner that makes it more user-friendly.
However, if you cut the front sight of an SKS to style it like an AK front sight, and painted the stock black, and removed and lost/destroyed the original magazine, then you have bubba'd it.
"Bubba'd" rifles/pistols are rifles/pistols that have been permanently altered in ways that did not improve performance. Anything else isn't bubba'd.