The police suspect a teenager named Joe of planning to murder his ex-girlfriend's entire family. The evidence is locked in Joe's computer. Failing to hack into the computer, the police find Joe's best friend Billy and gather some information:

1) Joe has put his ex's family members into 2 groups on a whiteboard as below:

Group 1:

Nancy (her cat)

Group 2:

Bobby (her pet snake)

2) Joe has used one of his friends' names as the computer's password. The names are:

  • Billy
  • Lilly
  • Kelly
  • Ally
  • Nancy

3) Joe has told Billy that his computer's password shares the same attribute that he used to categorize his ex's family.

4) A single failed attempt to login to Joe's computer will cause the computer to reformat, thus losing all the evidence.

It turns out to be a very simple logic and a smart detective quickly solves it and arrests Joe. The question is: what is the attribute Joe used to categorize his ex's family, and what is the password?

EDIT: I should have mentioned that the attribute helps to distinguish the password from the rest of the choice

Hint #1:

The Attribute does not necessarily relate to a word's spelling / length. Even the description of the ex's pet fits into the attribute it shares with the group.

  • 1
    $\begingroup$ Sounds like a pretty brutal guy, that Joe ... $\endgroup$ Mar 25, 2015 at 22:12
  • $\begingroup$ Thanks for the edit @randal'thor! Haha no offense to anyone named Joe out there! $\endgroup$
    – Alex
    Mar 25, 2015 at 22:12
  • $\begingroup$ What does "shares the same attribute" mean? $\endgroup$
    – Jack M
    Mar 25, 2015 at 22:13
  • 1
    $\begingroup$ @JackM that's why it is a brainteaser! $\endgroup$
    – Alex
    Mar 25, 2015 at 22:18
  • 3
    $\begingroup$ take the hard disk out, put it as slave(not master/not boot disk) to another computer and open all files there. If it still asks for a password, get 5 disks, copy his disk completely on the other ones and try each name on each separate disk. 5 names, 5 attempts, easy! :D $\endgroup$
    – Novarg
    Mar 26, 2015 at 8:30

1 Answer 1


The password is


My explanation:

Group 1 is all names/phrases that can be said without completely closing your mouth/touching both of your lips together. Group 2 is all names/phrases where you are required to touch both of your lips together (M in Mother, B in Brother, the middle "b" in Husband, etc.)

Given this connection, 4 of the 5 names (Lilly, Kelly, Ally, Nancy) match Group 1, while Billy is the only one that matches Group 2. Therefore, being the outlier, Billy must be the password.

  • $\begingroup$ Grrr, I was just typing out this exact answer when your one appeared! +1. The only slight problem is the hint, which mentions that even the pets' descriptions fit. "Cat" fits, and "pet snake" fits, but "snake" by itself doesn't. $\endgroup$
    – BenM
    Mar 26, 2015 at 19:44
  • $\begingroup$ Nicely done! Also @BenM, the hint mention the 'description' not the name itself. $\endgroup$
    – Alex
    Mar 26, 2015 at 19:47
  • 3
    $\begingroup$ Awesome riddle! This is such a weight off my mind. I've been trying to work this one out since I saw it pop up yesterday. $\endgroup$ Mar 26, 2015 at 20:01
  • $\begingroup$ @NonsenseSynapse thanks! I was starting to wonder if it's too boring as there are not many attempts, then yours pop up. I wonder what you've guessed thou, before going into the correct answer above $\endgroup$
    – Alex
    Mar 26, 2015 at 20:18
  • 1
    $\begingroup$ @Alex I think it was less of people not wanting to guess, and more of your riddle having a specific enough solution that it's hard to have a guess that matches your criteria, but is still incorrect. As for my process, I had a piece of scrap paper written out with the numerical values of every letter, seeing if there was a pattern there. Before your hint, I was comparing "Father" to "Mother" and "Brother." Since they all contained "ther," I figured there had to be something distinguishing "Fa" from "Mo/Bro, "and also unified "Mo/Bro." $\endgroup$ Mar 26, 2015 at 20:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.