Best Mate In The World. Just an abbreviation for those who have decided that it's too much trouble to write it out in full and so abbreviate it so everyone else doesn't have a clue what they're on about. You could also say BFITW - Best friend in the world, or BBFINTW - Best boyfriend in the world, or basically anything that suits your fancy. People aren't going to understand it anyway.

(P.S. I only found out what it meant after spending a few minutes guessing before my friend finally told me)
OMG Jms ur mi BMITW 4eva innit i lvs u!!!
by Loobyloolara February 3, 2007
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