I know the material off the back of my handPosted: January 6, 2020
A daughter was telling her father about a recent test. This is a mashup of “know it like the back of my hand” (extremely familiar with something) and “off the top of my head” (from memory without careful consideration). Either this is a malaphor or maybe she actually had the materials written on her hand? A big thanks to John Kooser for hearing this one.