If you ride a bike and you want to stick it to all the drivers around you, a subtle way in doing so would be to sew the Zero Per Gallon patch onto your messenger bag.
There’s an entire Flickr photoset of images showing how the Zero Per Gallon patch looks.
PS: Don’t buy a Crumpler, buy a Timbuk2!
PPS (or whatever the extra one is called): Bikes were on the list of things that white people like. LOI.