Let's talk about mu.

 

Since there are not many elaborated contributions to this discussion I'd like to add one:

https://www.youtube.com/watch?v=K_EsxukdNXM

As above, but here are a couple of serious videos ;)

In this one two monks present their understanding of (I'm 99% sure) the mu koan:
https://www.youtube.com/watch?v=sjyqGnWGftE

Here there's a bit more explanation.
https://www.youtube.com/watch?v=U2vF0dGNGmA

I was quite surprised that they say "mu" with the force that they do.

Intersting videos.  They do not seem to have cracked the code yet. 

This is the only instance I've seen Mu-chanted in a group setting, Shinzan Miyamae-lineage:
https://www.facebook.com/zenwaysyogameditation/videos/1758435424214494/
A fellow from the same group, after chanting Mu for 24 hours straight:
https://www.youtube.com/watch?v=Mu2A_waMquA

There are some references to shouting of Mu here and there. For example,
At Hosshinji, Tangen’s angst drove him to sit like a house on fire. For his first three years there, he wouldn’t lie down to sleep, instead doing zazen through the night. He would sometimes sit in a bamboo grove on the mountain behind the monastery, gripping one of the trunks and roaring, “MU! MU! MU!”
https://www.rzc.org/news/harada-tangen-roshi/