I assume you mean what that is called. The answer is improvisation, also know as improv.
This idiom means: stating something quickly and without thinking hard about it. It is believed to be derived in the middle of the 20th Century when Americans started usingthis expression. Thoughts...
Ab mit Deinem/Ihrem Kopf.
D'avec leurs tĂȘtes.
It means just offering an opinion from what a person can remember and without reference to other sources.