Fill the balloon full of air then let about one third of the air out.
sand shaft to remove oxide.
Oil the needle with 3 in one oil.
You may put tape where you are going to poke the balloon.
Stick needle slowly through the end with the most rubber.
Slowly push the needle through adding oil if needed.
Remove the needle and toss the balloon in the air then pop it with the needle before students realize air is leaking out the two holes you just made.