My Favourite Little Person, who turned 1 in November, loves to talk. She holds forth at length about the issues of the day, uttering surprisingly long and complex sequences of phonemes, complete with modulation, intonation, and gesticulation, that have everything in common with fluent human speech except for the fact that I don't understand a word of it. However, it is great fun to have a conversation with her anyway, asking her questions, seeing how she responds, ascribing intention and motivation to her vocalizations.
It occurs to me that this would be a good improv game.
You put a babbly baby on stage with the improv players, and cast the baby in a key role in the scene. For example, if the scene is set on a ship, the baby is the captain. Then the other players have to play out the scene in response to whatever the baby happens to say or do.
It would have enormous entertainment value, although I suspect most parents aren't willing to volunteer their babies as props in improv shows.