It is greek mythological term for a traveling person.
Mainly used in Britain to describe an undesirable. A real 'Dochas' is one that smells like a wet dog, is dripping with grease and is covered in a thick layer of pustous boils. Not one you would like to spend any time with what so ever. This person cannot hold a normal conversation and usually babbles and exaggerates the truth. Many say that 'Dochas' speaks in code because it is so hard to decipher.
For example, see Poogina.
'Man, I feel like a Dochas!"