Indeed, "X" does mark the spot - in this case, the final spot - in the twenty words that this quiz solicits. The remaining, arranged alphabetically, require suitable permutation prior to attachment of the letter "X" at the end of each. A perfect score here is "X"cellent!
""X" Marks the Spot,"
Word Ways: Vol. 44
, Article 13.
Available at: http://digitalcommons.butler.edu/wordways/vol44/iss2/13