Cabin fever is an idiomatic term for a claustrophobic reaction that takes place when a person or group is isolated and/or shut in, in a small space, with nothing to do, for an extended period.
Symptoms include restlessness, irritability, irrational frustration with everyday objects, forgetfulness, laughter, excessive sleeping, distrust of anyone they are with, and an urge to go outside even in the rain, snow or dark.
The result? Awesome Tshirt designs!