What are they trying to solve?

I was on the the train once, bored as hell (because trains in Romania are really slow) and at one point I hear 2 guys behind me, probably as bored as I was, talking about puzzles.
And I thought:
"Oh! I like puzzles. I should join them. I'm sure they won't mind. But wait...what if I have no idea what's it about and I look like a fool? I better eavesdrop a bit and but in only if I know something".
But a window was open and the noise from outside covered part of their conversation.

Guy1: Look at this (mmmmm). It has numbers and letters.
Guy2: it has to be a crossword.
Guy1: That's not possible because (mmmm). But they can be the moves for a Rubik cube.
Guy2: Pff...you're an (mmmm). There are only 6 letters in the Rubik cube moves. Maybe it's a matrix of something. Letters on (mmmm), numbers on (mmmm).
Guy1: Or a cipher? Man, I hate ciphers. Or a pattern?
Guy2: There are (mmmm), so this is probably not a rebus.

I this point I realized I have no idea what's this about and decided to shut up. Also, I'm a shy guy and I didn't ask them what's this about.
But I am still puzzled (pun intended). What was that about?

 In the light of the 2 answers I feel obligated to mention that the fact that letters and numbers are involved is not important.
And I remembered one of the guys saying at one point that they were trying to solve a puzzle from puzzling.stackexchange.com.
[/Edit]

Note: (mmmm) marks the parts I couldn't hear, but they are not really important. You can solve this without knowing what I missed. They are there only for dramatic effect.
Note 2: (not part of the puzzle, just "fun" fact): The trains in Romania are really, really slow.

• Singmaster notation for a 3x3x3 cube has $12$ letters: FRDBLUMESxyz and sometimes i is used instead of ' too. – Jonathan Allan Sep 23 '16 at 7:39
• @JonathanAllan. I guess they were both (mmmm) in this case. All 3 if you include me :D – Marius Sep 23 '16 at 7:40
• Maybe they are trying to solve the PSE puzzle titled 'What are they trying to solve?' – Tom Sep 23 '16 at 8:44
• @Tom, maybe you want to put this as an answer and elaborate a bit on in. – Marius Sep 23 '16 at 8:45

Just from the OP's comment this is maybe too literal but

I suppose a possibility is that two guys in a train could be reading this puzzle now and making the same statements as in the puzzle. This may be too self-referential and hope ok to post.

I guess this could only happen after the puzzle has been posted unless the OP was present when it was being created, or that Romania time is ahead of mine, or being on a train reminds me of special relativity and the fact they are going slow may be be an observer's effect of near light speed travel - I've stretched too far now. I was set up to answer this by Marius :)

• Close enough. They were trying to solve a "reverse-puzzle", not necessarily this one I posted. Boy, your imagination runs wild on special relativity and stuff :). – Marius Sep 23 '16 at 8:57
• Ahhh...I was just about to post this... – smriti Sep 23 '16 at 8:57

$\require{begingroup}\begingroup \def\T#1{\color{black}{\small\textsf{#1}}}$

$\T{Guy1: Look at this}$ new puzzle from Marius, whom I would like to meet someday.
$\phantom{\T{Guy1: }}$But where to start here? $\T{It has numbers and letters.}$

$\T{Guy2: It has to be a crossword.}$

$\T{Guy1: That's not possible because}$ it represents an ordered sequence of actions.
$\phantom{\T{Guy1: }}\T{But they can be the moves for a Rubik cube.}$

$\T{Guy2: Pff...you're an }$ algebraic myope. $\T{There are only 6 letters in the Rubik cube moves.}$
$\phantom{\T{Guy2: }}\T{Maybe it's a matrix of something. Letters on}$ the lefts of numbers,
$\phantom{\T{Guy2: }}\T{numbers on}$ the rights of letters and just before colons.

$\T{Guy1: Or a cipher? Man, I hate ciphers. Or a pattern?}$

$\T{Guy2: There are}$ no pictures, $\T{so this is probably not a rebus.}$

A fortnight of utter silence later, curiosity overcomes shyness and Marius thinks of something to say.

$\T{Our hero: Hey guys, aren't trains in Romania really really slow?}$

$\T{Guy1: Huh? Oh, hi, guy.}$ $\T{I was so busy mulling over what Guy2 last said, about rebuses,}$
$\phantom{\T{Guy1: }}\T{that...}$ $\T{Hey! You look a lot like that guy on the avatar. Are you...?}$

$\T{Our hero: Depends. What type of puzzle are you guys working on there?}$

$\T{Guy2: }$Hard to tell with all the (mmmm)bling. We don’t even know where to start.
$\phantom{\T{Guy2: }}\T{Aha! Just noticed}$ the tag. $\T{This must}$ recursively be a $\, \boxed{\,\raise-.1ex\textsf{reverse-puzzling}\,} \,$ puzzle.
$\phantom{\T{Guy2: }}\T{How delightfully clever!}$

$\T{Our hero: In that case, pleased to meet you. The name's Marius.}$ $\endgroup$

• Wasn't going to let this go to waste, having made it before seeing the accepted answer. – humn Sep 23 '16 at 9:35
• ha ha. are you Guy1 or Guy2? Thanks for filling in the blanks. I hope that "How clever" was not a sarcastic expression. If it was, please don't tell me. Let me feel good about myself. – Marius Sep 23 '16 at 10:29
• Sincerely stated, @Marius, downplayed even because I didn't want it to look hyped – humn Sep 23 '16 at 10:51
• Matter of fact, I first wanted to write a comment thanking you for letting us join you on a puzzling train ride (evoked some long ones in S/Finland for me), then thought of making a lighthearted nonsolution where I was yet another passenger puzzled by your spying on those guys. But each time a detail was needed it matched your narrative so well that what was really going on just took over the story. Very fun way to have a solution sneak up. – humn Sep 23 '16 at 10:56

A long shot is that they were reading:

the moves of a chess puzzle in algebraic notation. It has numbers and letters in it.

is it:

the moves of the game "battleships"

the numbers and letters are

the locations of the torpedoes to sink the ships.

more then 6 letters because

the field is 10 by 10.

• Yes the game is called battleships – Beastly Gerbil Sep 23 '16 at 7:19
• I see your point (somehow), but this is not what I had in mind. – Marius Sep 23 '16 at 7:25

(FOR FUN GUESS)

Could it possibly be

a train schedule? Or timetable for trains.

Numbers and Letters:

Depending on the train style/names, numbers are for time and platforms, letters for train names (e.g. 12:45 ==> A, P5 referring to Train A coming to Platform 5 at 12:45am)

Why are those 2 gentlemen saying that?

The trains are so slow that they had to make a joke on the timetable, pretending the information is part of a "puzzle".

• Ha ha...No, the train being slow is not part of the puzzle. Ha ha – Marius Sep 23 '16 at 8:26
• Darn, you really, really put emphasis on it, so that confused me :D – Keyur PATEL Sep 23 '16 at 8:33