As a cricket fan from India, I mostly know about everything there is to know about cricket. Except why a fielding position, Third Man, located behind the batsman on the right side(off side) near the boundary, is called "Third Man".
Also, two other positions, namely Gully (between slips & point) & silly mid-on/mid-off. Why Silly?
It's by no means definitive, but this link states that it's because, when overarm bowling was introduced, another fielder (to complement slip and point) was needed - this was the third fielder, hence third man.
This link, however, gives a subtly different interpretation.
The first link also gives these explanations:
Gully - Refers to the gap or 'gully' that exists between the slips and point
Cover - Refers to the position that 'covers' the point and middle of the wicket
Mid off and mid on - Shortenings of the terms 'middle wicket off' and 'middle wicket on'
Silly Mid On - the mid on is self explanatory, however it is believed that the silly refers to an old definition of silly, meaning 'defenceless'.
I've heard a different explanation for Third Man, which is that there are three 'stopping' positions 'wicket-keeper', 'long stop', and 'third man' behind the wicket.
