I posed that question on Twitter recently, and received just one response. Apparently, "engacho" means "hitches" or "pegs" in Spanish. That doesn't make much sense given the game's content and (what little I know of its) story, so I'm guessing something was lost in translation when the folks at publisher NAC Geographic Products Inc. chose Engacho! as a title.
Another possibility: They weren't thinking of Spanish when they decided to call their game Engacho! or they simply made up the word.
Regarding the former, the always reliable (ha!) Google suggested this word--えんがちょ--when I asked it to translate "engacho" from Japanese to English. It certainly sounds like the Google lady is saying "engacho," doesn't it? (Click on the link above and then "listen.") Also, Google's translation of えんがちょ is "for example I is wicked," which, while hilariously stilted, fits the game's theme fairly well.
Why am I running off at the mouth in regards to this rather disgusting--but still loads of fun--little puzzler? Well, I bought it recently, that's why. I can only play it on my computer (using an emulator) at the moment, as I don't yet own a Japanese PS1 or PS2, so I can't tell you too much about it--I hate playing games on my computer--but I can share a few photos of it.
For starters, here's the game's colorfully gross cover:
And here's the actual game disc, which I consider to be both cute and creative (the face is of the game's protagonist):
Oh, and remove the disc from its transparent tray and this is what you see:
(In case you're wondering: Yes, I'm completely incapable of taking a straight-on photo of a game.)
I'll share scans of the game's front and back covers when I review Engacho! as part of "The Great Gaymathon." In the meantime, check out this post for (a bit) more information.