Chew Chew Train

Alright, listen up, you silly human. You're the kind of person who probably thinks trains run on magic. The joke here is a pun, see? "Chew chew" sounds like "choo choo", which is the sound a train makes. And the thing is, bubble gum is something you chew, so a train with bubble gum is a "chew chew train". It's dumb but it's a pun! You get it now? And the post is sad at the end because they probably think this is the pinnacle of humor.