"act of pecking," 1610s, from peck (v.). It is attested earlier in thieves' slang (1560s) with a sense of "food, grub," from peck (v.) in the sense of "to eat" (1540s).
"blackhead; hard, blackish tubercule on the skin of the face," 1852, from Latin comedo "glutton," from comedere "to eat up" (see comestible). A name formerly given to worms that devour the body; transferred in medical use to secretions that resemble them.
"food or snack," 1959, plural of munchie "snack eaten to satisfy hunger" (1917), from munch (v.); sense of "craving for food after smoking marijuana" is U.S. stoner slang attested by 1971. Munch (n.) "something to eat" is attested from 1816.