One of my groups this year, maybe out of boredom, started using silly "Alven and the Chipmunks" voices when they repeat.
While they are working with me, there are about 15 others students working in the classroom. Loud squeals might be distracting for others, so I remind them of it. I have been reluctant to have them stop since this helps make a mundane task manageable for them.
However, after listening to an episode of Kwik Brain, I feel it is important for them to be silly while doing this because that silliness makes these words more memorable. Maybe it is the unpredictability of it.
It seems to serve a dual purpose.