In kendo, a tenugui is Japanese term for the cloth that is wrapped around the head to provide additional padding and sweat absorption underneath the men (helmet). There are a few observations about them.
One of the things that marks a newbie in bogu is the “rooster tail”. This is when the tenugui is improperly wrapped and sticks out of the back of the men. Rumour has it that if you go for grading with a rooster tail, you will fail. I’ve never seen this happen, but I’ve also seen a lot of people get admonished by senior students for not having their tenugui tied properly.
Another thing that marks a newbie is watching their tenugui slowly start to cover their eyes inside their men. This is a lot of fun, especially if they’re persistently continuing keiko without being able to really see you. Of course, this can be dangerous, so it’s a good idea to let them tie their tenugui properly.
It’s most considerate for all players when everyone’s equipment is tied properly so there is no time wasted during practice having to re-tie equipment. In tournament, one also wants to avoid the distraction that loose equipment can cause. I saw one junior tournament where a player used an equipment issue to completely remove their men and tenugui so everything could be re-tied, and the player got some much needed rest during that time as well. Sneaky, but it worked for him.
There are three main ways ways to tie a tenugui. I won’t get into details here, but here are some links to a few websites.
Taro Ariga, CEO of E-Bogu.com, showing how to tie tenugui two ways.
Video by xxxConanexxx on how to tie tenugui when you have long hair.
Video by Ladakh on how to fold tenugui with the “cap” method.