"6 B to an O in C" is a phrase used in a code-based mind game. The phrase itself translates to mean "Six balls to an over in cricket," and refers to the sport of cricket, which requires a player to deliver six bowls within an over.
Codes such as "6 B to an O in C" are sometimes used as part of intelligence tests to measure the brain's code-deciphering and recognition abilities by taking commonly known facts and displaying them in a coded format. These types of intelligence tests often include a series of similar codes, such as "26 L in the A," which translates to mean "26 letters in the alphabet." Another code commonly used in this type of intelligence test is "24 H in a D," which decodes to "24 hours in a day."
Organizations such as Mensa International often administer intelligence tests such as these. Mensa is a social organization consisting of individuals with above-average intelligence quotients. To receive admission to Mensa International, a candidate must prove that he has an intelligence quotient in the 98th percentile or higher. Candidates usually demonstrate this qualification by taking a series of tests, which may include code-deciphering tasks such as those described above.