"to make untidy, put in a state of disorder," 1837, American English, probably a variant of mess in its sense of "to disorder." It was attested earlier (1830) as a noun meaning "disturbance, state of confusion." Related: Mussed; mussing.
1510s, "of the color of blood, of a deep red color;" 1640s, "of or pertaining to blood," from Latin sanguineus "of blood, bloody," from sanguin-, stem of sanguis (see sanguinary).
"chaotic, disorderly," 1961, apparently from shamble in the sense "disorder" (see shambles), perhaps on model of symbolic.