With ProudClod. Half an hour to figure out what program I needed (fiddled around in Makou Reactor, Loveless, and WallMarket before I figured out what I needed), and another two minutes to find the string and change it.
FF7 is a mess to work with. Field text is sorted by screen in flevel.lgp (and the screens are not named in any convenient manner), battle text is part of enemy AI in scene.bin, and everything else is in kernel.bin. I guess it makes sense, having everything put together with the engine that uses it (and stuff that both engine uses like item text are in the only place that both engines access), but it's still a pain in the butt to work with. I remember working on a Pokémon Red hack years ago (I never released it because it was garbage), it was MUCH easier with similar tools to what we have for FF7, because the game itself was simpler. Being a Game Boy game, all the data was in a single binary, all the text was easily accessible from the same window without having to find where it was used first.
When I make some more significant progress, I'll start a proper thread for this in Game Tweaking. AFAIK there's no other comedy-oriented mods for this game, so this could be quite original and unique.