Badger in the mailbox

A term for an unexpected or unpredictable problem or issue which causes harm, physically, mentally, etc.
Can be used if the problem is self created or not.

Referential to the idea of a mailman’s opening a mailbox unknowingly containing an angered badger

(Self Created Problem) *Joe trips and hurts his nose*
Steve: Man, you really put the badger in the mailbox
Joe: I guess so

(Not self created) *Crazy girl destroys Steve’s car*
Steve: Man I really missed the badger in the mailbox there