The sidewalk snail barrier is when a group of 3 or more people are walking extra slow down a busy city sidewalk, spaced out with no room in between. This makes it nearly impossible for someone who walks at a normal pace to pass said group.
"Sorry I was late to work, boss. I was walking as fast as I could, but I ran into a sidewalk snail barrier."
by Punchy McAssface Jr. May 9, 2010