Gadarene swine the pigs into which Jesus cast the demons that had possessed a madman (see legion), and which as a result ran down a steep cliff into the sea and were killed; from this, Gadarene means involving or engaged in a headlong or potentially disastrous rush to do something.
And,taking it back a step:
Gadarene: being from Gadara
Gadara: Palestine town SE of Sea of Galilee

Gaberdine: ...
"Have you got a light, Mac?"
"No, but I've got a dark brown overcoat!"

I'll get me gaberdine!