Verb. To take private property without permission, (esp. written and intellectual), remove any inherent value under the delusion that they are making it "better," and pass it off as one's own for personal gain without bothering to obscure the real source.
When caught cooks sourcing, a person then becomes unreasonably arrogant, demands compensation for orchestrating the screw-over, and claims professional expertise on applicable cyber laws while demonstrating that they actually have less expertise than a teenage boy who just discovered there are things other than porn on the internet. See also: Griggs
My neighbor tried to cooks source my champion show dog. He stole Muffy out of my yard and started walking her around the neighborhood, right past my house. Then I received an invitation to the dog show, and a bill for the vet that spayed her! You should have heard him try to Griggs his way out of it: "Honestly, the dog was outside so it was public domain. You should be thanking me - I fixed her."