A term coined by Phillip K. Dick in the short story "Do Androids Dream of Electric Sheep?"
The word as used in that context refers to the collection of useless bits of trash we wallow in, all the paper and junk that is not recycled, and decaying entropic trash. It's what buildings become full of when only a few occupants remain, and it's what cities would become full of if they were to suddenly and permanently be emptied.
"Kipple is useless objects, like junk mail or match folders after you use the last match or gum wrappers or yesterday's homeopape. When nobody's around, kipple reproduces itself ... the entire universe is moving towards a final state of total, absolute kipple-ization."
- J.R. Isidore to Pris, "Do Androids Dream of Electric Sheep?/Blade Runner"
In the "Blade Runner" movie, J.R. is shown living alone with absolutely nothing but a huge collection of kipple to keep him occupied.
The most obvious breeding ground for kipple is the kitchen junk drawer. The second most obvious is the attic.