Dionysus,
The only thing I can figure is your grandma might be referring to an aftertaste? Like if the pizza made right before yours had anchovies (yuck) and you detect an anchovies-ish taste on your pizza.... it's said to be anchovies-eyish? But then again, you don't generally get to be old being no fool, so I ain't bout to fight with your grandma on her "unique colloquism," and I'd suggest you not either, cause she can still prolly swing a mean switch?
besides can't nobody make up words like us....I see this nere' bout daily here on GC!!