If people run riot, they behave in a way that is not controlled, running in all directions or being noisy or violent.

I dread them coming here because they let their kids run riot. 我害怕他们到访，因为他们任由孩子胡闹。

If your imagination runs riot, you have a lot of strange, exciting, or surprising thoughts.

My imagination was running riot, thinking of all the ways that I could spend the money. 我的思维象脱缰的野马，放任地想着可以花掉这笔钱的种种方法。