Do you need to tell your auto insurance the truth about an accident?

It happened at 12ish am. The owners (a married couple) of the vehicle are out of town and will return in 2 weeks. It's unoccupied and there were no witnesses either.

I got out of a home party (my friend's b-day), was heading back home and that's when it happened. Not major but I still hit their rear bumper and it was a small scrape.

Do I have to tell my insurance the truth about it? It's obvious why. Yet I still thought I could make it home with no problems. Even with dizziness I saw myself with good coordinations so I trusted myself.

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Can I just tell my insurance something else, that I accidentally hit their bumper and exclude the obvious part.
Do you need to tell your auto insurance the truth about an accident?
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