It's wrong to leave a small child unsupervised.
Billy is cooking and just now realized that he doesn't have any flour that he needs for dinner, he is currently watching his two year old son.
Billy needs to go to the supermarket.
Billy knocks on his neighbor's door and asks him to watch his kid for five minutes while he runs to the supermarket.
Billy tells his son he'll be right back and runs out to the supermarket.
The neighbor agrees, and Billy's son is feeling calm and safe.
Billy's son is afraid of staying alone and terrified the entire time.