I phoned him up on the spur of the moment.

我一时心动，给他打了电话。

《牛津词典》

He must have cooked up his scheme on the spur of the moment.

他肯定是即兴策划了他的方案。

《柯林斯英汉双解大词典》

Notice the spur of activity.

注意行为的变化。

youdao

Here is the song "The Switch and the Spur."

VOA: special.2009.02.06

"This isn't something that happens on the spur of the moment. It takes a great deal of planning and I think it is an indication the police are determined and doggedly pursuing the leads they got."

VOA: standard.2009.09.17

"For instance,we know that mental illness disorders like depression or alcohol use disorders play a major role in European countries, for instance" "But,we have to also look at Asian countries where impulsiveness plays a much more important role, which is that suicide can happen on the spur of the moment."

VOA: standard.2009.09.10

Was that something that just occurred to you on the spur of the moment?

BBC: News Online

The spur to the rethink is the acute shortage of affordable housing, particularly in London and the south-east.

ECONOMIST: Social housing

But, without the spur of an outraged public, Ms Collins is not optimistic about the prospects for reform.

ECONOMIST: The police