When someone says "My brain turned to mush during that unit test," they are using a metaphor to describe feeling overwhelmed or mentally exhausted by the difficulty of the test. This phrase suggests that the person's brain felt like it was unable to function properly, similar to how Superman's heat vision can cause things to melt or turn to mush. Using this metaphor helps convey the feeling of being unable to think clearly or process information effectively during a stressful or challenging situation. Overall, this phrase captures the sense of being mentally drained and struggling to perform at their best.
