Flag tape

From AmtWiki

Flag tape is the plastic ribbon surveyors use to make stakes and other objects. It makes excellent throw-away enchantment ribbons, berserk headbands, and scout bandages. It can also be used to make real or role-played terrain hazzards.

You can get flag tape (also called surveyors flagging tape) at your local Home Depot, Eagle Hardware, or Lowes. Hardware stores usually only carry yellow. You can also order flag tape online. The Industrial Safety Co (http://www.indlsafety.com/) sells flag tape for $1 a roll in solid Blue, White, Yellow, Orange, Pink, Green, and Red. Black and White checked flag tape used to be available, but has become more difficult to find.