Immune to the laws of physics and incapable of independent activity, the butthumper finds your rear bumper on an openstretch 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.
Someone who jumps from one relationship immediately into another one.
Serial monogamists can not stand to be alone and often suffer from vast commitment and insecurity issues.
Because they jump into relationships immediately after the previous one has ended, serial monogamists typically don't take the time to reflect on their behavior or why their previous relationships failed; thus, they end up making the same relationship mistakes over and over again.
Person 1: Damn, Dustin already has a new girlfriend?! It's only been two weeks since he broke up with his fiance! I think he's a sociopath.