A cause of difficulty, or potential embarrassment.
The outer skin of a banana, especially once removed from the rest of the banana, which may be slippery if stepped on.
A potential, unsuspected, hidden problem, hazard, or danger that is easily encountered but not immediately obvious.
A type of trap consisting of a concealed pit in the ground, which the victim is supposed to fall into and not be able to get out from.
An antipattern.
Subsidence below ground in a mine, which can cause the ground level above to drop.