Definition of bangtails:
(n) :
The tail of a horse or cow, allowed to grow out and then trimmed horizontally so as to form a tassel; a horse or cow having such a tail.
(n) :
(US) A racehorse.
(n) :
(slang) A prostitute.
(v) :
To shear off the hair horizontally at the end of a cow or horse's tail.
(n) :
(marketing) An envelope with a perforated flap on which promotional material is printed; the flap on such an envelope.