Name an angle complementary to Complementary angles add up to 90 degrees. COA is supplementary to AOE (they add up to 180) AOB is 90 degrees AOD is 180 degrees COB is complementary to COD. And because COD is congruent to AOE (because vertical angles are congruent), COB is also complementary to AOE. So our answer is COB.
Mad Libs was invented in 1953 by Leonard Stern and Roger Price. Stern and Price co-created the game, but couldn't agree on a name for their invention. No name was chosen until five years later (1958), when Stern and Price were eating eggs Benedict at a restaurant in New York City.
The most famous Mad Hatter, of course, is the one from the Mad Tea Party in Alice in Wonderland, the partner of the March Hare. Both mad, of course. But Lewis Carroll did not invent the phrase, although he did create the character. The phrases mad as a hatter and mad as a March hare were common at the time Lewis Carroll wrote (1865 was the first publication date of Alice). The phrase had been in common use in 1837, almost 30 years earlier.