I See Signs All The Time

If I am going to print a sign I'm going to have it proof read. This one is subtle and actually took my mind working all at once to figure out what was wrong. In the process I pissed and shat myself (to access the prefrontal cortex I have to bypass the cingulate gyrus which controls my bladder function). It's like a brain barf in other words. Yes, -20% off is a double negative implying that I have to pay a fifth more. Almost as fun as the Aroma Coffee sign in Edinburgh which read 'You're cup of coffee' implying that I was a cup of coffee. Genius.