Depends how you use it. But some ideas are:
unfortunate circumstance
tragedy
cataclysm
catastrophe
mishap
calamity
disaster
hope that helps
happenAlso occur or two words ...will be
Event
her word for bad food
trigger event
Another word for strange event or equation
another word for terrible
Incident.
Another word for bad is naughty
preliminary
awesome
another word for bad language it curses or dirty talk
Another word for 'very bad' is, "Heinous" (HAY nuss). Another word is, "Dire".