You're lying in bed at night when your mail-order bride suddenly sits up beside you and asks "What was that?"
"What was what?" you ask.
"I thought I heard a moo," she says.
"Go to sleep. It's just your imagination."
Then you hear it too.
"It came from downstairs!"
You get up, grab your chainsaw off the dresser and quietly walk downstairs with the chainsaw whirring away quietly.
As if out of nowhere, a cow charges you, trampling you to death.
Never attempt to take on a cow that goes moo in the night yourself. Call the proper authorities immediately.