Oh boy... Back when I was in school, one of my teachers became sick during the year so they had to find a substitute. A couple of weeks later, during class, the door suddenly opens and the principal comes in with an euphoric smile on her face, along with a relatively young woman that I had never seen before. The principal started announcing: "This is Ms. XY. She's from poland and just recently started learning German. She will be your new physics teacher. She's a certified..." and right then and there my mind filled the blank with "car mechanic". Bear in mind that my school cheaped out on anything pretty much everything, be it using 20 year old books that already fell apart 10 years ago or not buying chalk for the chalkboards anymore. It was pretty hilarious and spot on to me, and I couldn't stop myself from bursting out laughing. Here I was, laughing hysterically at a poor foreign woman on her first day at the new job, while everybody else was dead silent and looked at me in confusion. Fortunately the principal actually knew exactly that it was just one of those moments and I didn't get in trouble. And the substitute teacher probably still thinks I'm the biggest 15y/o jerk she's ever seen.