Premium members can wear any block as a hat. Previously you had to hold the block and type /hat. In the recent update by Cayorion this was changed.
Just equip the block in your inventory like a regular helmet 
This is just one of many premium features. Learn more here:
http://massivecraft.com/premium
Awesome now is it much easier to wear hats
I just love that picture
You is number 3 from left side. Him with the tnt
Yeah, next it’llbe the animation of taking the hat on and off hehe
That’s a great idea Dexeron, *Tips hat* :p