Breastfeeding

Listen here, bud. This joke implies that people are skinny because they don't have a family to "breastfeed" on. The joke plays on the idea that access to nourishment, specifically breastfeeding, is the reason people maintain weight. I know you probably don't have people around you, but people usually eat food to gain weight, duh! Also, "breastfeed" in a family context is more like a baby thing... you should already know this. This joke is supposed to be funny because it's so dumb.