Craig Thomson's definitions

sour loser

The origin of the word "sore loser". This much makes more sense than using the phrase with a "sore" in it. Sour comes from the phrase, "Sour grape". A big misconception of that figure of speech.
To whine or sour grape

Derick is such a sour loser, that he slams the plates in the gym, because his team lost the finals.

by Craig Thomson October 2, 2013