Fighting is very, very dangerous. Unless you are one hundred percent confident that you are safe, it is unwise to ever let your guard down.
Mind you, anyone who enters into a ring (or cage) to fight someone, is doing it with the explicit intention of inflicting pain. And when you are standing opposite someone who you know is there just to inflict pain, protect yourself at all times is probably a pretty sage bit of advice to hold on to.
The bald dude in the video below didn’t get that memo. Rather than just fighting his opponent, he decided to get overly arrogant about the whole thing and let the other guy get some free licks in. You can probably guess what happened next.
The lesson here? Don't be stupid.