meaning to go cop or buy something that you are going to turn around and sell for a higher price...usually drugs, blackmarket goods, or something bought from a crackhead or smoker.
" man I just sold my last one, but I am gonna get down later today"
Said after someone says something that one goes against or doesn't agree with; something irrelevant or completely unbelievable. Kill it (definition #7) may also be added as a way to get the point across clearer.