Halflings are called this because they are half the size of humans. While small, halflings are quite capable, and those who think them easy targets soon learn painful and sharp lessons.
A Barbaric proverb, stemming from Dungeons and Dragons, Implying that when the obvious fails, do something unexpected, the saying apparently started as an inside joke but now has spread to the general geek/RPG community
DM: There appears to be a secret door in that wall
Druid: *throws rock*
DML Nothing happens
Druid: Come on guys lets go
Barbarian: Can I throw the Halfling at it?
Rogue(hafling):NOOOOOOOO DM: sure
Rogue: Noooooo
Barbarian: To late, I get annitiative
DM the door opens and the halfing takes 2 points of damage
Barbarian: When in doubt, throw the Halfling