Crazy huge dude

Ok, my ex girlfriend is going out with this crazy-ingly huge muscled dude and he wants to kick my ass and I am puny and scared. So I need to know where and how I can get a knife that is small and how I can carry it around my body at all times as to use it in case of defense (and defense only!).

I'm seriously scared and hope you guys can tell me how I can do this?

lol, you people are all over thinking this junk.  You don't need a gun or a knife or poison needles.  Here are a few better ideas:

-Keys.  Hold them in your hand and use them to slash.  Or attach them to a lanyard so you can swing them like a mace, the more mass the better.

-Walking stick/cane/umbrella.  Great for poking, and swinging.  Your best bet in a confrontation would be to poke him in the stomach from a distances and then strike him while he's out of breath.  You may also wish to consider keeping a baseball bat in your car.

-Box cutter.  Easily concealable and you can keep it hidden until the moment you strike.  Better than a knife because the courts probably won't consider it a "deadly weapon."  Just don't try to cut his throat or neck.

-Pocket full of change.  wtf can change do?  Pull out a handful of change and throw it at his face.  I might not hurt him, but it will distract him long enough for you to attack or start running (but you better hope you're quick enough).

-Roll of nickels.  Hold them in your hand to add extra mass.  Essentially the same effect as brass knuckles, though not quite as good.

-Can't fight?
Don't yell for help.  Yell "FIRE!"  People are more likely to come if they here fire.
Also, try screaming something like, "I can't breathe!"  It's unexpected and your assailent might be so surprised that he may stop whatever he's doing long enough for you to kick him in the balls and run.