When something big, loud, shaky, or forceful happens, we may hear car alarms going off outside or offscreen to indicate the magnitude of this event. If it's really big, it'll set off all the car alarms in the area.
Similar to Disturbed Doves, That Poor Cat.
Loud sounds can indeed shake a car enough to set off the alarm, making this Truth in Television.
Not to be confused with extreme damage to a [...] [tvtropes.org]