1782, "highway robber," probably from dialectal verb scamp "to roam" (1753, perhaps from 16c.), which is shortened from scamper. By 1808 in a general sense of "fugitive, vagabond, swindler, mean villain;" used in the affectionate sense of "rascal" since 1837.
"do in a hasty manner, perform in a slipshod or perfunctory way," 1837, probably from a dialect word, perhaps from a Scandinavian source (OED compares Old Norse skemma "to shorten, make shorter," from skammr "short; brief; lately"), or a blend of scant and skimp [Klein], or a back-formation from scamper. Related: Scamped; scamping.