bumpercasting 

Expressing your point of view through an over abundance of bumper-stickers.

I get you are pro-life, but do you need all the bumpercasting? I can't see what color your car is.

bumpercasting by BiggJoe December 20, 2010

bumpergating 

To tailgate someone so that you can read their bumper stickers.

There was this guy in front of me whose bumper was covered with funny ass stickers...I almost hit him because I was bumpergating him.

bumpergating by Geoff Lilley January 24, 2008