A quirky habit is an unusual behavior that someone may have. It is often seen as a unique trait that sets them apart from others. The crossword solution for the term QUIRKY HABIT is TIC, which stands for Transient Ischemic Attack. This is a type of neurological disorder that can cause sudden and temporary loss of blood flow to the brain, resulting in a variety of symptoms such as muscle twitching, facial tics, and involuntary movements.