Any thought that hits the person's brain with such impact it feels as if he/she has been struck by a brick being thrown at them. These can come as single bricks, dump trucks full of bricks, or brick roads depending on the meaningfullness or amount of thought that goes into it.
Ohhhh man that was a huge brick.
What was it?
I just thought about how I was feeling the first day I fell for you.

Note: you just say brick, not mental brick, it is assumed when you explain the thought that it is a mental brick.
by Jake Who? February 7, 2009
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