One of my friends was dating a blonde girl that wasn't too bright to say the least. Often she would come up with the most stupid comments that at first got us all laughing, but after a while also became a bit annoying to some.
One day we were sitting in a pool hall talking. The blonde participated in the discussion, and when she came up with an, unusually, stupid comment, ( even for her ) one of my friends couldn't take it anymore.
So he said to her 'You must have vacuum in your head'. This upset her. She looked at him for a couple of seconds and replied, 'At least it's better than nothing'.