On Big Nate you go to the Klassic Komix shop and go to a man in a yellow shirt. Talk to him.
Go and collect the pieces of the comic. There is one at the Pop-in shoppe on the sofa upstairs,
one on the third electric pole (at the top), one at the school where the broken loudspeaker is,
one in the science lab, one at the camera shop thing, one at the playground hovering in mid-air at
the top and one at Puffin Point. Put the pieces all together and go to the man in the Klassic Komix
shop. He will give you a pack of bubble gum.