Wingmen

She prevents interference

There's usually another girl trying to work the same hot guy that you want to take home.  Or sometimes his "friend" will be doing all he can to make sure your target goes home alone.  A good wingman can help you overcome this pick, commonly known as the c*ck-block.  

She'll do so by running her own interference and engaging, at close range, the meddling girl or guy.

If it's a girl, your wingman might get in her way physically and box her out, so you can move in.  If it's a guy, she'll start a conversation and keep it going long enough for you to work your magic.