Answer: Frank
The name Frank, in this case, was short for "Frankincense", a perfume given to the Christ child by the Magi in the Bible. The boys' mother, searching for a Bible name starting with "F", settled on "... Frankincense... because he smelled so sweet". Evidently, the brothers had given Frank such a hard time about his name for so long, that merely mentioning the word "Frankincense" was enough to turn him dangerously berserk.