Why do you spell picnickers with a K?

The word "picnickers" is spelled with a "K" because it's the plural form of "picnicker."

The word "picnicker" itself comes from the word "picnic," which is believed to have originated from the French phrase "pique-nique," meaning "to pick at."

Since the word "picnic" ends with a "K" sound, it's consistent with English spelling rules to add an "S" to the end to create the plural form, "picnickers."