crumple

crumple /ˈkrʌmpəl/ verb
crumples; crumpled; crumpling
crumple
/ˈkrʌmpəl/
verb
crumples; crumpled; crumpling
Britannica Dictionary definition of CRUMPLE
1 
a  [+ object] : to press or squeeze (something) so that it is no longer flat or smooth
— often + up
b  [no object] : to become wrinkled or bent : to stop being smooth or flat
2 
[no object] : to suddenly bend and fall