Hand in glove / The sun shines out of our behindsThere's a Catalan expression which says the same thing as "hand in glove" or "thick as thieves", only in a far more colourful way. You can describe two people as being cul i merda or "ass and shit". (If you want to clean this up, you say they are carn i ungla or "flesh and fingernail".)
asshole In an active sense, an overbearing, arrogant, and inconsiderate person. In a passive sense, a shmuck or loser, e.g. "that poor asshole". But even in this case, there's more of a sense that the person has done something to deserve being shat upon than there is with those terms.
dick Only used in an active sense for someone who acts inconsiderately and uncharitably.
Thoughts?
I once knew a soft-spoken public-school type from the Midlands who never cursed. It didn't upset him, he just seemed unable to do it. I remember him once prompting me to repeat one of my most vulgar outbursts by saying, "You know the one, 'You're a [pause] and a [pause] so go...'" "You mean 'You're a dick and an asshole so go FUCK yourself!'?" At the time, I got a kick at playing the casually vulgar American to his repressed Englishman. It was similar to the charge I got when reading an American-British dictionary and finding this definition for motherfucker: "An expletive so vulgar that it has no British equivalent." I was all like "YEAHHH! WE KICK YOUR LIMEY ASS!"