Archived request from the wiki:

Bulb horn

• Other names: Bicycle horn, taxi horn, squeeze horn
• Wikipedia: Vehicle horn
• Family: Winds/Other
• Description: a small metal horn sounded by squeezing a rubber bulb (often found on bicycles and early automobiles)
• Appears on:
  1. Straight Outta Lynwood Track 5 as horn
  2. Alpocalypse Played by Jon "Bermuda" Schwartz on track 5, credited as horn