Used as a superlative in the rare casethat two expletives will not suffice, to describe someone so utterly contemptible and stupidthat the utterer has to search her mind for a sufficiently potent approbrium.
What?!! You sold your twelve year old sister to a Romanian sex ring mafioso for half a cabbage? You... You... BUGGERFUCKTWAT!!!!!!
exclamation, contraction of "don't even think about it", uttered during copulation with a frigidfemale that has just felt your cockbrush her anus. A signal that you did not buy her enough alcohol prior to engaging in the sex act.
Oh yeah honey! How about some of this?
Damn.... hey you want a break? I make a mean vodka-lemonade.