"Can't" is a famous "danger word" for learners of English - every language has them! Other examples in English are "sheet" and "beach". You should pronounce these words clearly to avoid embarrassment. In some accents of BrEng "can't" rhymes with "front", but I suggest you avoid this yourself. In standard BrEng "can't" rhymes with "aunt", "slant", "chant", etc. ---/ʌ/ (c*nt, front, blunt, stunt)--- This sound is very "neutral" and is close to the "schwa" (ə) sound. Th ---/a:/ (can't, aunt, plant, grant)--- In this sound your jaw is slightly lower and the tongue much further back in the mouth. Also very important: the vowel is longer than /ʌ/ If you want further practice between these two sounds, I suggest you Google search "ʌ ə minimal pairs", there are plenty of fun and simple tongue twisters you can try.

absolutely not. can't has "a" / cunt has "u" If you can say "lamp" and "lump,' you know the difference.

"Well, I was referring to the British version of the verb 'can't' which they tend to say with a 'u', don't they?" No, not at all! Nonsense. Completely untrue. Wherever did you get that idea from? In standard British English 'can't' is pronounced with a long 'a'. In RP, 'can't rhymes with 'plant'. Imagine it had an 'h' in it - 'cahnt'. A long, open 'aa' sound. Or if you're familiar with the IPA, 'can't' is pronounced /ka:nt/ in GBE. This is completely different from the other word, which rhymes with 'hunt' and 'runt'. These words have a short, closed 'u' sound, transcribed as /ʌ/ in the IPA. No native English speaker, whatever their accent, would confuse the two words. What's interesting, though, is that this same question has been asked before by a Russian speaker. Is there a Russian coursebook or website somewhere that's putting out this misinformation, I wonder?

For 2 people speaking English with the same accent there is a obvious difference between the pronunciation. The same is true for any English speaking country no matter what accent they have.

All I can add to this is, don't call a woman the second word unless you want to get bashed over the head with something quite heavy !