Seriously, who likes a know-it-all? There you are minding your own business, and suddenly a guy tells you how many jellybeans there are in a jar. He knows this based on the size of one jellybean and the size of the jar. Anyone wants to know how many M&M’s there are in a packet?  

Useless information it may be, and it is worse when one keeps spewing information like that. It really gets on one’s nerves.