Definitions of sandbag:

• noun:   a bag filled with sand; used as a weapon or to build walls or as ballast
• verb:   protect or strengthen with sandbags; stop up

  Example: "The residents sandbagged the beach front"

• verb:   treat harshly or unfairly
• verb:   downplay one's ability (towards others) in a game in order to deceive, as in gambling
• verb:   hit something or somebody as if with a sandbag
• verb:   compel by coercion, threats, or crude means

  Example: "They sandbagged him to make dinner for everyone"