The Urban dictionary says:
Background: Australian. Given to us by Crocodile Dundee:
A spontaneous journey through the wilderness of one’s choosing in an effort to satisfy one’s itchy feet, a need to be elsewhere, the craving for the open road, that space over the horizon…yes… something like that… you can’t quite touch it so you have to go find it because it’s you just know it’s there…Or maybe it just feels good to go walking around … 😉 Yeah. It’s WALKABOUT.