The Graveyard Duck
Videogames' Greatest Mystery Revealed
That dialogue window has two sentences:
"Get a silk bag from the graveyard."
"Duck to live longer."
It is a fact that in Simon's Quest, you get the silk bag from a graveyard. Moreover, it is the town due left from the town that dialogue is from.
As for what it means to "duck to live longer", many mysteries in that game are beaten by ducking while holding a crystal. This is the only way to progress at a cliff, for instance. While "duck to make further progress" might be more literal, "living longer" could be considered to be an abstract metaphor for "making progress." We might be justified in having some skepticism in that interpretation, since, if that is indeed intended to be a clue for the ducking mystery, it is very oblique. But EVERY clue in Simon's Quest is oblique at best.
The other objection to my interpretation is that there is no punctuation separating the two sentences from each other (though there is a line break). However, it is not as though Simon's Quest is otherwise free of grammatical errors...
Update: It seems I have to put an end to my fun here. While this may have seemed to me to be a plausible theory, the evidence is that even in the Japanese version, "duck" referred to the animal, not the verb. See discussion here, and a page on the subject here.