I must confess to having accidently pulled the mixture to fully lean on a PA28, after climbing out of Le Touquet over the sea, and doing FREDA checks.
Why... I couldn't tell you, I had meant to apply carb heat (completely different shape/colour lever) and for some bizzare reason pulled the mixture control back to lean... I soon put it back to rich mind you! It sure made my passenger (an instructor!!) sit up and take notice.
I've never done it before or again since. Suppose it was 'classic' brain fade!