As for “merkin”, over at wt lu we use the term generally as to describe someone as an “ idiot” although often in a humorous vein depending on context and sometimes as abuse
“ Shut up
@The Rosco you merkin”
Would be someone telling Rozzes that his point was not agreed to. But no disrespect intended. In fact, it’s a light and friendly comment, endearing, warm and welcoming.
Rozzes replies: “ F…you dickhead” and it’s a signal for a meaningful and happy discussion based on mutual respect.
“Ivan Cleary is a merkin”
Means that the user thinks that Ivan Cleary is a scumbag of the highest order. A lying two faced greedy rat. Not to be trusted. A bad kind of a human being. A selfish self flagellating flip. An idiot son obsessed bonehead sprog of Satan. That’s not true of course and is an honest opinion some may hold. Not me that’s for sure.
So it’s all context.