A campus legend from San Jose State College:
A friend of mine tells this about her brother Jack, a sometime student. Jack found himself sitting in the classroom during an important examination with two blue books, a pen, and a question he couldn’t answer. Being naturally bright, if lazy, he thought of the following solution. In one of the blue books he wrote a letter to his mother, telling her that he had finished writing his exam early but was waiting for a friend in the same class and so was taking the opportunity to write to her. He apologized for not writing sooner but said he’d been studying very hard for this instructor, who was a nice guy but had pretty high standards. When the time was up he handed in this blue book and left in a hurry with the unused one. He hurried to his text, wrote an answer, and then put the blue book in an envelope and mailed it to his mother in Boston. When the instructor found the letter he called Jack, who explained that he had written in two blue books and must have got them mixed up and if the instructor had the letter, the answer must be in the mail on the way to Boston. He offered to call his mother in Boston and have her send the envelope back as soon as she got it. He did, she did, and the blue book was sent back, with the inner envelope postmarked the day of the test and the outer envelope postmarked Boston.
— Lew Girdler, “The Legend of the Second Blue Book,” Western Folklore 29:2 (1970), 111-113