A more thorough explanation:

The Twinkie defense is a legal strategy that uses an unconventional argument to defend a defendant in a criminal trial. The term originated from the 1979 trial of Dan White, a San Francisco politician, who was charged with first-degree murder. During the trial, a psychiatrist testified that White's consumption of sugary foods, such as Twinkies, could lead to diminished capacity. White's lawyer used this testimony to argue that White lacked the premeditation and deliberation elements necessary to establish first-degree murder. As a result, White was convicted of a lighter offense of involuntary manslaughter.

The legitimacy of Twinkie defenses has been debated. After White's trial, the California legislature amended its penal code to soften the intent requirements for first-degree murder, so subsequent defendants could not rely on the Twinkie defense. The term "Twinkie defense" has been used in various contexts, such as describing "outrageous" medical-related defenses. The term has also been associated with a defendant's right to choose their own counsel.

Imagine a person is on trial for stealing a car. Their lawyer argues that they were sleepwalking at the time of the theft and, therefore, should not be held responsible for their actions. This is an example of a Twinkie defense because it is an unconventional argument that seeks to diminish the defendant's responsibility for their actions.