I would have yelled out
"You better back it up!"
... good idea, just record it, don't call the police or anything... Having the priorities at good place.
I would have yelled out
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"
"You better back it up!"