What is the meaning of scrunch up?

verb

• Sit on one's heels.
  • usage: "In some cultures, the women give birth while squatting"; "The children hunkered down to protect themselves from the sandstorm"
  • synonyms: squat, crouch, scrunch, hunker, hunker down
• Make wrinkles or creases on a smooth surface; make a pressed, folded or wrinkled line in.
  • usage: "The dress got wrinkled"; "crease the paper like this to make a crane"
  • synonyms: wrinkle, ruckle, crease, crinkle, scrunch, crisp