Consider this definition for a moment:
"Contrary to most definitions, the “bitch” is describing the “slap” rather than the destination.
A Bitch Slap is a sharp, openhanded, stinging, yet generally benign slap – similar to being slapped by a bitch. When you “bitch slap” someone, you are slapping him or her like a woman would! Scratching, hair pulling, cursing, and crying generally follow a well-placed bitch slap. "
The tertiary Te user will uncharacteristically snap back with Te.. "fuck your thoughts and feelings, this doesn't work, it's not efficient". But when they use it, it is not the full scope of Te your used to dealing with (full powered te punch) it's a "bitch-slap" because we do not have full access to the function.
But your right, being rude does not = Te bitch slap. It is typically accompanied with rudeness because the ENFP is fueled to TE bitch slap through Fi violation. Despite how it is executed, the message stands "this doesn't work. It is ineffective. External evidence is contrary to what you are doing, saying, etc."
I don't think an Fi bitch-slap is even possible, as it is internal. Do you INTJ's inwardly bitch-slap yourself? heehee