Are these firm enough to "nail" golf tees into soft foam? We need these for our sons 3rd birthday party. Thanks

maybe. they are foam themselves. My son actually broke it right away, pulled the head right off the hammer. I bought it for a Fix it Felix Halloween Costume.

What are the dimensions of this hammer?

length: 6", hammer head length: 3 5/8", as a smaller woman my grip reaches around the handle. It is the perfect for our 2 yr old class when we study Noah building the ark. It was a great find for me.

Does it squeak when you bang it??

No, it doesn't. It is is a solid piece of foam.

If an adult threw this at somebody would it hurt them?

No, it shouldn't hurt anyone if they get hit with it. They might not appreciate being hit with it, but the construction is bendable foam and should not hurt and adult. It may possibly be hard to throw it due to the light weight and foam structure. I gave this away as a joke gift, so I don't have it in my possession any longer to try it out.