Goodbye ... because it pains me.......

surrender as it is not in my dictionarey of life.

My least favourite word would be 'vicinity' because I occasionally mispronounce it as "vis-nis-city" (well I *used to*, anyway for a brief period)

acknowledgment - very difficult write and to say this word

Well that all depends, but what is very annoying is when people say "Um... Um...." a lot this can be very annoying, though I am sure this is something done in most languages. For most English speaking people, what is most annoying is when people use improper English or advanced words but do not know how to use them in a proper sentence.