Back when I got off active duty, I went back to school for a 2nd degree in CS (I had put in 250+ resumes and applications and gotten 1 interview - there was a recession in Texas in 88). Since my Ag degree at A&M didn't require a foreign language, and the CS degree at UT Austin did, I chose Spanish (duh).
4 of us CS majors ended up in the same M-F 8 a.m. class. So what the heck.... we all took the same 4 semesters together. The final for the 4th semester required a 15 minute conversation with the Instructor monitoring. We worked like hell to script something up and practiced for days. Came time for the exam and we were ready. 11 minutes into the conversation, the Instructor stopped us and asked "Just what language are you 4 speaking?" Being the leader/instigator of our group (I was 34 and the others 19/20) I said, "Why, Spanish, of course." She said "I'm hearing the words but it doesn't sound much like any Spanish I know."
A little more question asking revealed that our 4 instructors were a Blond Jewish female from San Diego CA who spoke pure Spanish Castilian, a male native Peruvian, a male native Brazilian (his Spanish had Brazilian Portuguese influences), and a finally a female from Argentina. As an example of our "Spanish", we had 3 different words for banana (which we used interchangeably when speaking with each other along with many others), the vocabulary we learned each semester was spoken with the accent of the Instructor we learned it under with our Texas accent influencing everything.
She said that we obviously had held a conversation, the words were in Spanish, if not making any sense to her and that the best she could give us was a "B". We said "Thank you" and she left. We then did happy dances because we were hoping to pull out a "C".

We ended up with "A"s overall because of the written exams.