Which movie is “knock on the head” from?

The clip at the top of this page is from Be Here Now (2015).

knock on the head

In Be Here Now (2015), one line is: “It wasn't until I got to the ward that Professor Gibson said, "We need to knock this on the head.”

to stop sth from happening; to stop doing sth

informal · British · Heard in 2 movies

knock sth on the head
to stop sth from happening; to stop doing sth
The recession knocked on the head any idea of expanding the company.

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

It wasn't until I got to the ward that Professor Gibson said, "We need to knock this on the head.

Said in 8 films · #1