Red herrings... in menu commands!

This is a cruel joke I'm contemplating using... 

I have 3 PCs with wings, and I have the "FLY" ability (used to fly over obstacles, not for world-map navigation)

If you try to use it with one PC it will work fine.

Using it with the second wing'd character you get her muttering she's afraid of heights...

The third character you get a "tried... and failed..." message (hey, dont expect so much from a child! :p )

(and yes the last two actually tie into the chracters themselves, it's not just thrown in)

Is this too cruel of a joke? Should the option only appear when the 1 PC who can actively do it is in the party?

This is largely (but not, I think, entirely) down to personal preference.  I think I would be seriously hacked off if it appears that I'm being given a useless skill - though I admit, I'm a bit unsure about how you intend to implement this.  It reads as though this is going to be in the main menu.  Is that correct?  If it is, why is it?  Why is it not in the character's skill menu?  One risk would be that if I've tried this with 2 characters and have repeatedly failed, I may not bother trying it with the third. 

I think, though, that to some extent you have answered your own question with your description of this as a "cruel" joke.  Why are you setting up the player for failure?  Why do you want to be cruel?

See, that would be awesome if you didn't tell everybody about it.

Not quite... there will be obstacles on the map screens that have a special tile next to them, stepping on that tile and pressing the trigger button will pop up a menu "Skills" that will list the available skills based on who's in the party (Telekenesis, Summon, Fly, Magic, Strength) and of course the correct skill will cause an animation to play and the obstacle to be removed (or the player will be moved to the other side if the obstacle has to be flown over)

Why? Really? You must be young, I was raised on DND ---

http://tvtropes.org/pmwiki/pmwiki.php/Main/KillerGameMaster

And the games I played tended to be ---

http://tvtropes.org/pmwiki/pmwiki.php/Main/NintendoHard

While I do tone it down somewhat, I still make things difficult and an edge of sadism (though thankfully humorous sadism)

I highly doubt anyone on here will have any interest in playing my game...

I'm also toying with the idea of the command only being useable once on these red herrings and then disappearing from them... a little less cruel but maintained the initial joke.

Just read the articles you linked to.  With the Killer Game Master, I would be one of those exercising the option to "just get up and go home".  Not my idea of fun at all.  I'm just so glad I wasn't around then.  I might have been put off for good.

Different times, man... and "killer DM" actually pushes the limits, most DMs, even the harsh ones, aren't pure evil incarnate.

But yeah, I try to be a lot more lenient in my video games compared to TT games (I'm known for punishing players who dont think things through by altering dungeons on the fly --- you stopped checking all the illusionary holes to make sure they're illusions? whoops! That next one's real! (even though it wasn't real on my map before *evil grin*)) I think the "Fly doesnt for for X and Y" is more a bonus joke than a cruel twist for this reason (especially if I do decide to only use it once then switch it off for those two PCs --- and it's not like they're useless, one PC has Summon (unique skill) and the other has Pick Lock (semi-unique in that the black mage has Knock which does the same thing, but eats up MP and isn't 100% effective, while Pick Lock has no cost --- though to even that out I may have like a 5% chance the lockpick breaks and has to be replaced... not sure on that yet...))

Not necessarily cruel. If they have the potential to do it, but can't for some reason, I think it's okay. And I like to see a bit of humour in a game (ie - afraid of heights).

Not to mention, if the character by all appearances SHOULD be able to do something, but can't - that's plenty room for character development right there; they might not need a big, epic story arc to overcome their fear of flying or whatever, but a few subsequent mentions of why they can't perform, as it were, could be enough to raise the quality of the story.