go haywire: get excited; go out of control
Haywire has meant substandard or out of whack since the beginning of the twentieth century. Some of the earliest recorded uses come from logging. A 1905 Forestry Bureau Bulletin defines haywire outfit as "a contemptuous term for loggers with poor logging equipment." Haywire was first applied to defective equipment or a poorly functioning system, but by the 1920s it had started to mean going crazy. A typical example comes from the 1936 mystery novel Flowers for the Judge by British writer Margery Allingham: "I suppose some wives would have gone haywire by this time."
The most common explanation of the origin of go haywire is that haywire—used for bundling bales of hay—has a tendency to twist up, making it difficult to work with. Another possibility is that pieces of old haywire were often used for makeshift repairs in earlier times. This explanation would account for why the expression is first recorded in use among loggers rather than farmers.
These days computers, as well as other entities like the stock market, are often described as going haywire. Human beings can also still go haywire—and often do.