There is this fairly common thing I've noticed, when a multiglot is talking to someone about languages, and they say "say something in x", suddenly all words in that language leave my head and I can't think of anything to say. I've noticed more than just me having this problem. Most people who've had this happen say, "What do you want me to say?" which I think works as something to focus on, especially if it's a common or beginner phrase. Maybe it has something to do with nervousness.

Why can't people who speak multiple languages remember anything when asked by a monolingual?