The art of using a sharpened tool to slitthe neck of a person you hate, sharpened tools can range from knifes to sharpened toothbrushs.
Billy hated Joe, so while they were in jail Billy sharpened his tooth brush and went to shank a hoe. Later that day Joe was found dead at the foot of his cell bed
Londoner slang for "Oi, izz dinner time. Come over, we're having fish en chips." Saying "I will shank you bitch" in London often means "Do you want to get some coffee with me?" or "I'll get you some food." depending on the individual's tone.