1. A nasty paste formed from sweat and lint that forms under the female breast
2. Pieces of food or other debris that are caught between or under the female breast, usually associated with elderly women
After her workout, Kathy noticed an excess of titty litter caked under her boobs.
Grandma is starting to smell from all of the titty litter she's dropped and forgoten.
A person you hate intensely not because they deserve such hatred but because they serve as a focus for your general hatred. A healthy way to dispense with excess animosity.
Jake's not really that big an asshole. He just serves as my hate sink.