crumple
     v 1: fall apart; "the building crimbled after the explosion";
          "Negociations broke down" [syn: {crumble}, {tumble}, {break
          down}, {collapse}]
     2: fold or collapse; "His knees buckled" [syn: {buckle}]
     3: to gather something into small wrinkles or folds; "She
        puckered her lips" [syn: {pucker}, {rumple}, {cockle}, {knit}]
     4: become wrinkled or crumpled or creased; "This fabric won't
        wrinkle" [syn: {rumple}, {wrinkle}, {crease}, {crinkle}]
Source: WordNet® 2.0