This question is too vague, and needs more information. There are many brain teasers!
AN INSIDE JOB
Once in a blue moon
At a glance
To answer this question the brain teaser must be provided. The type of brain teaser or the place of the brain teaser doesnÕt give enough information for someone not looking at the brain teaser to be able to solve it.
A joke, puzzle, or brain teaser.
That isn't a brain teaser
I love you
Possibly it is 'by and large'.