either as an insult towards someone who is being a tool or douche
or if an object or situation is crap or rubbish.
it can even be emphasised by adding "proper" in front of it!!
or "mate, what was that film like you went to see??", effects where good, but storyline was a bit Joppa, to be honest!"
or going back to work after having 10 days off is going to be proper Joppa!!