It's something I've often thought about whilst gazing at my pen, "I wonder what this little fella here is for?". 

Well now, thanks to Dave's World, I have my answer. Well sort of. 

It's all to do with air pressure that helps the ink flow. Now for ya! Though Dave does second guess himself. 

Mr Moore also teaches us what a three-way duel is called, shocks us with his 'frostnip' knowledge and tells us the scientific name for toasting food. 

A fountain of knowledge he is!

Check out the fun in full by pressing the play button in the image at the top of the page.