Amitoria, I can assure you that these two words are NOT pronounced the same way in British English, or in any other variety of English. Think about it logically. Do you think it is likely that an everyday modal verb like 'can't', which we all say a dozen times a day, would really have an identical pronunciation to the most vulgar and offensive taboo word in the language? Of course it isn't! In BBC English, RP English, or the 'standard' pronunciation you hear if you click the GB audio button on any online dictionary, the word 'can't' is pronounced with a long 'a' sound. It begins the same as the RP pronunciation of 'car'. It's a long vowel sound made with the tongue in a very low position. If you say 'caah', with a long 'a' sound, then add 'nt', you'll get the standard GB pronunciation of 'can't'. The other word rhymes with 'hunt' or 'runt'. This vowel /ʌ/ is a short sound, pronounced with the tongue in a mid-position. There is no chance of confusing this with 'can't'.

Haaaa, I recall answering a question like this before. :) It's pretty simple - if you have this confusion, then you're probably following the British pronunciation for "can't". The easy solution is that you must pronounce "can't" with a long vowel sound. We never shorten it unless we're making a lewd joke. One sound is long (and means "not able"/"may not"), the other is short (and a vulgar word). So, time to practise those long vowels. :)

http://dictionary.cambridge.org/dictionary/english/can-t?q=Can%27t+ The pronunciation of 'can't' is different in American and British English. Both pronunciations are on that webpage so you can hear the difference. The vowel sound between these two words is different. http://dictionary.cambridge.org/dictionary/english/cunt?q=Cunt This word is considered one of the most offensive, if not the most offensive word in the English language, so naturally it is important that you can distinguish them!