Dexx is a word used to describe something. It can be used to describe something that is good, bad, insane or it can be used as an insult. It is very addictive to use. Dexx can be changed to dexxed and dexxstion.
Emma: That is so dex (good or bad depending on what it is)
Amy: Taylor your face is dexxed! (insult)
Check this out, it is complete dexxstion. (insane)