I read this in the Baltimore Sun last month. The article provided the following situation as the lede. I think it makes a fine explanation:
At 7:40 p.m. Jan. 17, a police officer pulled his marked cruiser to a corner on Woodbine Avenue in Northwest Baltimore, got out and approached Antonio Walker-Bey, a face so familiar he knew him by his nickname. The officer, standing three to five feet away, said he saw the young man toss something to the ground and quickly walk away.I think the term can probably be used when the drugs are planted, but I also think it's probably meant to be commonly used as the abandonment of one's stash.
A common case, an unending war, The Baltimore Sun