<i>Verb</i>
Coined by Te'Devan Kurzweil, mindflanking is the art of saying something that nobody expects and expanding their mind in doing so.
Where a generally common/idiomatic exchange may be occuring, you instead say something totally whacked out and unexpected. You break a social convention and their whole perception of that convention is altered.

I'm not sure about the validity of the perception altering, but it's fun.