You're hitting on the realknockout of a babe in a bar, and as always there this one person (speed bump) that gets in your way to cockblock.
I probably could have picked up this babe but she was with her girlfriend usually the overweight or not too cute chick with her (can be a boyfriend as well) and each time I put on the gas I had her speed bump in the way.
It's used when your into a girl or a boy and you find out she or him has a boyfriend or Girlfriend . it's just a speed bump the boy friend or girl friend between you and that person.
Jon: that girl there is pretty hot.
Shane: Ya man but she has a boyfriend Jon: No worries man that's just a speed bump.