Well apparently the sums are to shut down the associative part of the brain and they get progressively harder to make sure. Then when they throw in the coloured tool question the associative part springs to life in it's supposedly default state. Red is the most popular colour. Hammer is the most popular tool. Apparently no where near 98% answer that though and it's just a meme to make sure it gets passed around on forums with nothing better to do on bank holidays. And we were all corrupted with talk of black spanners.
So what other undocumented BB codes are there?
Oh dear, I'm amongst the 2% who have an abnormal mind!
Just looked at the spoiler, and I'm not!
I had blue screwdriver too!
Just did it again .... got a blue Lance Armstrong!
Ruins the test when you read the comments first. Came up with green screwdriver.