A hedgerow can refer to one's pubic hair, therefore a bustle in your hedgerow can mean to become sexually aroused.
John had a bustle in his hedgerow for Jane as soon as he saw her.
- from:
http://www.urbandictionary.com/define.php?term=A+BUSTLE+IN+YOUR+HEDGEROW
Critics of rock and roll songs (and of Led Zeppelin in particular) have alleged[8] that a backward message is recorded into "Stairway to Heaven." The message, which allegedly occurs during the middle section of the song ("If there's a bustle in your hedgerow, don't be alarmed now..."), is purported to contain Satanic references:
Oh here's to my sweet Satan.
The one whose little path would make me sad, whose power is Satan.
He'll give those with him 666.
There was a little toolshed where he made us suffer, sad Satan.
-from: http://en.wikipedia.org/wiki/Stairway_to_heaven