It refers to a technique used in older hardware to display bitmaped images. Instead of storing the color in the pixel's memory location, a CLUT based system stores an index that refers to a table of component color values.CLUTs are also refered to as palettes.
A mullet mound.
Something that makes a clean shaven man look like Burt Reynolds if he went down on it.
"I have a clut."
"A few more months and I've got a clut."