There was a discussion on here recentIy about stupid answers on quiz shows - weII I think the girI on Tipping Point Iast night takes the biscuit! Question was who organised the first package tour in 1841 - she said British Airways!
It's easy to sit on your sofa at home and shout at the TV, but a studio is very intimidating place, and the rabbit / headlights interface can easily occur.
So to be fair, it's not stupidity, it's mind-freeze and panic.