If you go down in the woods today, you'd better go in disguise,
In drainpipe trousers, fingertip coats, and don't forget your knives,
Don't bother to wash, cos it mighthe da rain,
And don't forget your bicycle chain,
Today's the day the Teddy boys have their picnic.

That's the version I heard, as a 1970s Ted in Oldham, Lancashire, England.