1 definition by bullshark

Top Definition
Immune to the laws of physics and incapable of independent activity, the butthumper finds your rear bumper on an open stretch of highway, and stays there. The asshole may be using you as a shield against radar, or as a fuel-mileage aid, but usually he/she is talking on the phone and relying on you to scan the road for them.
Ten lanes of superhighway to drive on and this jerk has to tailgate me. What a butthumper.
by bullshark April 01, 2008

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