I can't get the image out of my head of this poor kid cupping milk onto his massively swollen eyes after getting pepper-sprayed as a bit on this radio show I used to work for about 15 years ago.

This dude was in some SERIOUS pain. 

I found some old mace or pepper spray, (I believe Mace is actually a brand name), in one of our old junk drawers recently and I didn't know what to do with it. I learned it has a shelf life of about 4 years.

Oleoresin capsicum is a naturally occurring substance derived from hot peppers. OC Pepper causes an intense burning sensation to the skin, eyes and throat upon contact. Mace® Brand defense sprays are available in different strengths to satisfy virtually every requirement. -mace.com

ANYWAY...

I didn't know if you could carry pepper spray in Massachusetts. This state is pretty strict on some self-defense laws.

HOWEVER...

In Massachusetts, persons over the age of 18, CAN carry Mace or pepper spray for self-defense. There are some restrictions, though, like if you're a  convicted felon, according to mass.gov.

SOME FAQ'S INCLUDE

1. Can your attacker die from it? Although super painful, medical treatment is not necessary and your eyes should clear up on their own.
2. Will it permanently hurt your eyes? No, but effects can last up to 45 minutes.
3. What will alleviate the pain? Flushing with water, diluted baking soda, or milk can help.

Also, the makers of Mace do not suggest using any sort of wasp repellent for use of self-defense.