Quiz: Remember the definition of mal de mer?
1916, American English, "stupid person," perhaps a variant of English dialect goff "foolish clown" (1869), from 16c. goffe, probably from Middle French goffe "awkward, stupid," of uncertain origin. Or English goffe may be from Middle English goffen "speak in a frivolous manner," possibly from Old English gegaf "buffoonery," and gaffetung "scolding." Sense of "a blunder" is c.1954, probably influenced by gaffe.
"waste time," 1932; "make a mistake," 1941, from goof (n.). Goof off "loaf" is also from 1941. Related: Goofed; goofing.
To pass one's time idly and pleasantly; potter about; shirk duty; goof around: My goofing off in the final period had knocked down a possible A average/ Are you trying to tell me my son is goofing off? (WWII armed forces)
[fr British dialect goof, goff, ''fool'']