The heap
The fallacy can be described in the form of a conversation:
Q: Does one grain of wheat form a heap? A: No. Q: If we add one, do two grains of wheat form a heap? A: No. Q: If we add one, do three grains of wheat form a heap? A: No. ... Q: If we add one, do one hundred grains of wheat form a heap? A: No. Q: Therefore, no matter how many grains of wheat we add, we will never have a heap. Therefore, heaps don't exist!
So now we have The Fallacy of the Files