Have your chosen sticks or straws ready. I cut mine in half so that they were size-appropriate.
I got my paper straws at Bed, Bath and Beyond. They are super cheap with a 20% off coupon!
Slowly press the straws or sticks into the bananas after you've cut them and stood them up. They will slide nicely into them. Just make sure to check your piercing direction because you don't want to go in at the wrong angle and bust out the side.
Once you're done, pop them into the freezer for a couple hours. :)