A Log is is an item featured in Putt-Putt Saves the Zoo.
Putt-Putt will need the log in order to complete the raft and venture through the waters of Jungleland. Putt-Putt will find the log after he enters the Grasslands as the log is blocking him from going further. Putt-Putt will need to take the log in order to clear his way. After that, Putt-Putt will need to get back to the incomplete raft in Jungleland and use the log to complete the raft.
In the demo, the log is automatically present because there, Putt-Putt can't even go to the snakes' exhibit.
Sam uses the log to disguise himself as a tree by passing through three old and grumpy trees, despite that fact that his head is stuck. Each time Sam enters the garden past the trees or returns to Otto, he will automatically get out of the log after some initial struggling (he also complains about how it's hot inside).