I was once giving a RIS to a German PPL, who decided to fly around the UK with his son on holiday. With no instrument rating and a poor met forecast from the back of a newspaper, he inadvertantly became IMC and began to get iced up. All of a sudden his confident ICAO standard language dived faster into his native tongue than a Stuka pilot! Fortunately for him and his brown stained pants he was tuned into luckiest frequency in UK. As I speak fluent German, I understood every word of transmissions. After about 20 minutes of reassuring him and gentle instructions, I managed to get him down on an SRA totally auf deutsch! Just as I went into auto-gable, the supervisor gave me one piece of advice before continuing with the approach- if you fv*k this up you're toast! Thankfully the jerry made it safely onto the piano keys. I wonder who would have done the tape transcript if it went pear-shaped!