Actually, having grown in a farm myself, it is nothing out of the ordinary. Of course the chicken made a ruckus since it was been killed.... Probably by either strangulation, neck twisting or beheading... The hanging upside down part, is to drain the blood... And wait, killing a chicken is nothing compared to what is involved in killing a pig or a cow...
Nowadays we live so removed from how meat is actually obtained, processed etc, that it may seem "alien" to us...