[identity profile] lostcarpark.livejournal.com 2004-05-10 09:58 am (UTC)(link)
Wait! I know this one...

[identity profile] lostcarpark.livejournal.com 2004-05-10 11:04 am (UTC)(link)
Er, to get to the other side?

Or maybe it's a variant on this one:

Q. Why did the chicken cross the road?

A. Because the evil impearilist republicans had hunted, mined and polluted its natural habitats leaving a 6-lane highway as its only remaining forraging ground...