merkin is unique in Australia tho, and it hardly ever applies to a woman for being a woman.
The casualisation of it has watered it down to either a light hearted greeting amongst mates or an idiot regardless of what you are.
Merkin has become the new bastard. I remember when bastard was still regarded as rude but was often a term of endearment among mates, where the word merkin now sits. The Irish are equally happy using merkin but still frown on the use of bastard as you’re questioning the morals of one’s mother.