Correct:

1)"Let's eat, kids, Jimmy shouted.

2) Attention: Bathroom only for elderly,pregnant, and children.

3) I want strawberry milk, fries and nuggets.

4) We're learning how to cut and paste, kids.

5) Hunters when hunting, pedestrians use walk trails.

Incorrect:

1) "Let's eat kids,"Jimmy shouted.

2) Attention: Bathroom only for elderly pregnant children.

3) I want strawberry milk fries and nuggets.

4) We're learning how to cut and paste kids.

5)Hunters when hunting pedestrians use walk trails.

Why is it incorrect?

1) There is no comma before kids. Jim doesn't want to eat them.

2)there is no comma between persons. It's not possible.

3) There is no comma between strawberry milk and fries. It would taste weird.

4) There is no comma after paste. We don't want to cut and paste kids.

5) There is no comma between hunting and pedestrians. It would be bad if people were being hunted.