What does a sideways black and white American flag mean?

What do you mean by “sideways”? Flags are typically flown with the longer side (the “length”in vexillogy) flying, (landscape mode, if you will), as influenced by the wind. It's that wind, even if imaginary, that determines how the flag is displayed on a uniform or aircraft or ship. read more

The subdued color flag has now been transformed to a simple black and white flag, with a stripe of numerous colors, to “honor” fallen personnel of the several military, uniformed, and civil service forces. Each color, for those of a specific force. The easy ones to recall are: BLUE - police, RED - firemen. read more

The black and white U.S. Flag is essentially use of the flag to an alternate purpose, which is forbidden. What it is would actually be “advertising” your sorrow, drawing attention to your corps and its loss(es). read more