DEMMING: Sorry. What was that?
CASTLE: The Plains Indians considered it an act of bravery to get close enough to one of their enemies to touch them with a coup stick. Is my hair...?
DEMMING: Looks good.
Incidentally, I checked who wrote the episodes. Three different writers did them. Either it's a coincidence or someone--the producers? Nathan Fillion?--is inserting the Indian references.
For more on the subject, see Sacagawea in Castle and Maya Mummy in Castle.