This improvisation can also be done with real guests (or collegues), with real conversations. You “translate” what the other says by using you’re fantasy, in a real language or not. A lot of variations is possible, also depending on your own knowledge of the languages and inspiration. You can add up fun with non-verbal signs and face-expressions!
I do it also with collegues who speak Arab or Hindi in our break. Nobody understands them (included me), but I’m so kind to ‘translate’ for my colleagues. Ofcourse you use similar sounds, so when somebedy says ‘tingelingeling’, you translate it as ‘bell’ or ‘phone’.
Take care, not everybody likes to be fake-dubbed That’s why it might be safer to do it with colleagues (warned or not warned by you) in front of the guests.
Here somebody speaks ‘Swedish’ about a Volvo and the other has to “translate”. It comes from Whose line is it anyway and the game is called expert translation.
This idea is also used in one of my favorite films ‘La vita è bella’