Someone I knew once was fond of the asking "Capiche ?" anytime he explained something at length which was often. I figured from context that the word meant something like "Do you understand ?" and never really bothered to look it up.
More recently, I came across copasetic in a meeting and followed by an email to me. While it was easy to guess meaning from context, I had to make sure because I was responding to a client so I waited to reply until I looked it up.
In a social context directional understanding of an unfamiliar word usually suffices but one hesitates to take the same liberty in the workplace. Both situations involved unfamiliar words and expected a response from me. It is almost as if words and language intrinsically don't aid or impede communication as much as our initial response to unfamiliarity.