a piece of paper that has been chewed and then rolled into a ball to be thrown or shot at someone

to quickly suggest ideas to be discussed without thinking about them carefully

I'm just spitballing here. 我就是在这里随口说说。

The writers sat around for an hour, spitballing ideas for a character. 编剧们围坐了一个小时，信口讨论着一个角色。