A couple months ago I started training again for the first time in about 4 years, and about two weeks in I had to chop off my shoulder length hair cause it was driving me nuts when I was rolling.
Now I want it back. Guys with long hair, or ladies, whats the best way to deal with long hair on the mat?
A girl we train with puts her hair in two little buns similar to how Rousey does it. I guess there's a tutorial on YouTube how to do it quickly. Might look kind of gay if you're a guy though. 
If you have long hair then I guess that wouldn't be a concern anyway
Make sure you tie it up well....nothing grosser than another mans sweaty hair in your mouth. 
For Kurt O
I chopped mine off
My wife found a picture of some Brazilian jiu-jitsu gals and they all had super long hair, In a high ponytail braid.
She swears by it now, never a problem.
A dude here with some tips. Had the same issue when I first started training and had to chop it all off. I now have shoulder length hair tied up in a bun and tucked into a rugby scrum helmet. Search for it on amazon. Soft and durable for both ur training partners and yourself. Goes into the shower with me after training and gently washed with shampoo. Just use some athletic tape around the Velcro chin strap to cut down on irritation.
Luchador mask? Either that or cornrows.
davey24 - A dude here with some tips. Had the same issue when I first started training and had to chop it all off. I now have shoulder length hair tied up in a bun and tucked into a rugby scrum helmet. Search for it on amazon. Soft and durable for both ur training partners and yourself. Goes into the shower with me after training and gently washed with shampoo. Just use some athletic tape around the Velcro chin strap to cut down on irritation.Lol
I have long hair and I found pony tail sucks especially when I invert alot, and it comes undone. I Top knot my hair and it doesn't come undone.
Not long hair but a long beard, here. Shit gets pulled out all the time. But I'm still a BOSS with it, so it stays.
I always tied mine up in a bun on the top of my head. don't do it in the back because 1. you get caught in more chokes and 2. it's super uncomfortable if you have to put your head on the group (i.e. bridge).
I would bend over and gather all of my hair. Then i would twist it until it twisted down like a bun. I also used 2 thick hair ties to secure the bun...one at the base and one that covered the twisted up hair. Some rolls it comes out and other times it would last a couple of rolls. depending how hard you are going and if the other person is attacking your head.
I had long hair twice (grew it out to donate to locks of love). Cut it both time and realized it is not worth keeping the hair. It is such a pain in the ass.
Just make sure to condition well and it'll flow and slip through all situations.
Plus you'll get easy subs while your bros are busy sniffing your gorgeous hair.