Simply, it's a bare tree trunk, still rooted in the ground.
The formidable thing is, because it's kinda skinny, yes, it ... sways!
AwwWWWwwwWWWWWww!

Conquering all fears, one climbs on it, stands on it for as long as we can,
and jumps into thin air, trying to hit the blue bag,
if possible hit the ... chicken!

Fear is an awful feeling!
But one can conquer it!
To be fearless! It can be done!

... We learned that, very well, today!