Two pieces of memory actually touching each other or you touching memory that you don't actually own, in which case the computer doesn't really know what to do and just, bam.

两块内存相互覆盖,或者你覆盖了不存在的内存，那样的话计算机不知道,该怎么做，只有崩溃。

哈佛公开课 - 计算机科学课程节选