Unctuous
Theory: Asymmetric negative g rolling overstress can cause permanent deformations within a wing's attachment structure.
Saw the end result of this one but do not have any pictures but the wing was definitely deformed. The garden shed engineer might call it corrugated:
During a test flight from Boscombe Down, a drop tank became insecure after a bolt sheared off and fell out, causing the drop tank to oscillate violently, resulting in momentary loss of control. After regainin control, the pilot was able to return to Boscombe for a safe emergency landing, however, CAT 4 damage was sustained to the wing.