Display messed up

My 2 yr old son was messing around on the keyboard and magically hit something to make the display all funky looking (very dark and high contrast) going into the display settings doesn't help. what could he have hit, and how do I reset it back to normal. It is only on my settings, when my wife logs on hers are fine.

Thanks

Press and hold control + option + command, then toggle the number 8.

Amazing how kids and cats can find those things isn't it.