fight shy

bun fight

A debate or disagreement, usually with several parties involved, often political in nature.

few cards shy of a full deck

Mentally deranged; demented; insane.

fight a losing battle

To attempt a task or other endeavor in which there is no chance that it will succeed.

fight fire with fire

To respond to an attack with a similar or identical counter-attack (e.g. to respond to gunfire with reciprocal gunfire).

fight fires

To deal with urgent matters and minor emergencies rather than longer-term work.

fight for one's life

To be in danger of dying (as a result of injury, illness etc.).

fight one's corner

To vigorously promote or defend one's interests, views, etc.

shy bladder

An inability to urinate in the presence of others.