We most often use these words and expressions in the heat of emotions, without really thinking about how they are written. Meanwhile, despite their harsh purpose, swear words are also built into the system of the language, obey its logic and exist according to the same rules as completely literary vocabulary. We talk about spelling and the origin of expressive nouns, adverbs and interjections. If we swear, then competently and consciously! This and other expressive slang words based on the noun “fig” are very often written together, but in fact they obey the rule according to which adverbial combinations formed from nouns with the prepositions “before”, “for”, “on”, “with” , “without”, “by” must be written separately. However, in our complex language there are practically no rules without exceptions, and the spelling of nouns that turn into adverbs is one of the difficult places: “until death”, but “up to the top”, “abroad”, but “married”. But in this case, in the spelling dictionaries, a norm with separate spelling is fixed – to the fig, to the fig, to the fig. But as for the adverbs “don't care” and “don't care”, the opinions of experts differ: in some dictionaries there is a continuous spelling, in others – separate. There is also a third version – if the case ending is preserved in the word, it is written separately (no matter what), and if the ending is abbreviated, then it is continuous (don't care). This abbreviated version of the expression “hell knows what” is often found in oral speech, and it is usually written as they hear – “damn what”. In order not to be mistaken, you need to know how this construction is formed: the particle “those” is attached to the word “damn”, which should be written with a hyphen (damn what, damn where). According to the rule, any words with particles -de, -te, -ka, -then, -s are written exactly like this: just those times, come on, what a beauty! 
1. On fig
2. Damn it
3. Go to hell
It would seem that everything is simple here, but in books and dictionaries published before the middle of the 20th century, there is usually a variant with “o” – “to hell with it!” Only after the adoption of the Rules of Russian Spelling and Punctuation in 1956 was the spelling of this abusive word through “ё” fixed, and now it obeys the rule known to everyone from elementary school: in the root after hissing under stress, “ё” is written, not “o”. By the way, the same thing happened with the word “acorn” – earlier it was also written through “o”. And today – what the hell are acorns?
4. Moron
This offensive word is spelled with an unstressed “e” and nothing else, because it comes from the Latin debilis – “weak”, “weak”. Once it was completely neutral and was used only in the medical environment to refer to patients suffering from a mild degree of mental retardation, but today it has gone beyond a purely professional framework, has acquired a negative connotation and has become used in relation to stupid, slow-witted people.
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5. Cretin
Through “e” the word “nerd”, borrowed from the French, is also written. From the original language, cretin is now translated as “stupid, blockhead, jerk, simpleton,” but once this term was also a medical diagnosis – the name of people with a delay in physical and mental development caused by a lack of thyroid hormones. The word appeared in the French Alps, whose inhabitants suffered from a lack of iodine, and in the local dialect cretin sounded harmless and meant “Christian” (from the Latin christianus) – something like our “wretched”, “God's man”. 10 words popular with modern children. Do you know what they mean?
6. Yo-mine!
An expressive interjection expressing extreme surprise, bewilderment or even indignation should be written with a hyphen. This veiled curse consists of two parts: the first letter of an obscene expression similar in meaning and a consonant “decent” continuation. The logic is something like this: in a fit of anger, annoyance or amazement, a person will shout out the first letter of many Russian curses, and when he comes to his senses, he will say something decent in rhyme. Many other substitutes for rough vocabulary also begin with “yo”: ёprst, Christmas trees, sticks, Yoshkin’s cat, and even the opera theater.