The second octave is played by overblowing. Very popular for traditional Celtic music. Can be made of a variety of materials and in various keys, but more commonly found in wood or metal versions in the key of D, often with plastic mouthpiece.
Whistles are portable, cheap, readily available, and easy to play.
Relatively few people play the tabor pipe compared to the whistle, its nearest relative, but it enjoys considerable popularity among street performers of the Renaissance Faire and historical reenactment type, largely because it leaves one hand free. I bought a wooden whistle, but it wooden whistle. So I bought a steel whistle, but it steel wooden whistle. Then I bought a tinwhistle, and now I tinwhistle. Make a mute for your whistle when other people are around.