Archived request from the wiki:

Siren whistle

• Other links: http://www.youtube.com/watch?v=0pNWVy-yGFg
• Family: Winds/Other instruments
• Description: a plastic or metal whistle designed to sound like an emergency siren
• Appears on:
  1. Straight Outta Lynwood Played by Jon "Bermuda" Schwartz on tracks 2 and 5, credited as kazoo
  2. Alpocalypse Played by Jon "Bermuda" Schwartz on track 5, credited as whistle