Okay I have been arguing constantly with a native Russian speaker (who as I am with English, doesn't understand the rules, so when I say nominative, accusative its completely over her head). My argument was that Мужчина declines and acts like a female word in every way, but when you use adjectives you use the male versions. But at least this word can only ever refer to a man.

Now the word Крошка as far as I know just means Baby. and as with words like Врач can be used for both males and females.

So I'm asking is the phrase "Мой сладкий крошка" valid if you had a baby boy? I understand maybe it could sound weird and other words are available but I am just asking if it is valid/legal haha.