Definitions of slug:

• noun:   any of various terrestrial gastropods having an elongated slimy body and no external shell
• noun:   a projectile that is fired from a gun
• noun:   an idle slothful person
• verb:   strike heavily, especially with the fist or a bat

  Example: "He slugged me so hard that I passed out"

• verb:   be idle; exist in a changeless situation

  Example: "He slugged in bed all morning"