Personal Space

I rarely like for people to be so close to me that you are invading my personal space unless
1. I am sleeping with you (for the people that are part of my church family -or my grandmother- reading this, I have only slept with somebody once and that resulted in my daughter. *cough, cough*)
or
2. I am your mother and you are my precious baby girl.
Other than that, I don't like people to touch me or be very close to me. I'm not really a fan of PDA, and only on a full moon do I decide to be all cuddly with the boyfriend.
So when I get in line at my neighborhood Speedway with a 20 oz white chocolate cappucheapo (see http://en.wikipedia.org/wiki/Cappuccino )and a big greasy man with a thinned out, grease stained t-shirt with funky chewing tobacco breathe and pee colored, fried gray hair stands exactly one foot away from me, I'm expected to get uncomfortable right? I am expected to step forward so that I may again regain my personal space, right? But what happens when said gross man STEPS FORWARD IN MY PERSONAL SPACE AGAIN TOO? Should I then just turn around and release all my pent up rage from having to work with a team of complete morons and having a to deal with the stee-you-pid father of my child? Or should I just haul off and knee him in the family jewels? How about throw my steaming hot cup of cappucheapo in his face?
Seriously, I don't know how to deal with this type of behavior.