A plank bridge which breaks if the player is carrying something when he goes across it. Pushing anything over the bridge is forbidden outright.

"One Short Plank"
The East Jungle is a room. The plank bridge is west of the East Jungle and east of the West Jungle. The plank is an open unopenable door. "A precarious plank bridge extends [if the location is West Jungle]east[otherwise]west[end if] across the chasm." The description of the plank is "Extremely fragile and precarious."
Instead of going through the plank when the player is carrying something:
   say "You step gingerly across the plank, which bows under your weight. But your meagre possessions are the straw which breaks the camel's back!";
   end the story.
After going through the plank:
   say "You step gingerly across the plank, grateful that you're not burdened.";
   continue the action.
There is a feather in the East Jungle.

But indeed, why stop there?

The gigantic stone ball is a thing in the West Jungle. It is pushable between rooms.
Before going through the plank with something:
   say "Surely you jest." instead.
Test me with "w / e / w / push ball e / e / get feather / w".
Test me with "w / e / w / push ball e / e / get feather / w".
East Jungle
A precarious plank bridge extends west across the chasm.

You can also see a feather here.

>(Testing.)

>[1] w
You step gingerly across the plank, grateful that you're not burdened.

West Jungle
A precarious plank bridge extends east across the chasm.

You can also see a gigantic stone ball here.

>[2] e
You step gingerly across the plank, grateful that you're not burdened.

East Jungle
A precarious plank bridge extends west across the chasm.

You can also see a feather here.

>[3] w
You step gingerly across the plank, grateful that you're not burdened.

West Jungle
A precarious plank bridge extends east across the chasm.

You can also see a gigantic stone ball here.

>[4] push ball e
Surely you jest.

>[5] e
You step gingerly across the plank, grateful that you're not burdened.

East Jungle
A precarious plank bridge extends west across the chasm.

You can also see a feather here.

>[6] get feather
Taken.

>[7] w
You step gingerly across the plank, which bows under your weight. But your meagre possessions are the straw which breaks the camel's back!



*** The End ***