Big Blue appears as an extremely overweight Zomberry, wearing a brown shirt and hat on the Member's Only card. However, in Zomberry Island, he appears to be wearing a blueberry juice stained singlet and has messy hair.
Big Blue originally started out as a members only item in the Poptropica Store. It allowed you to expand into a fat Zomberry, which is similar to the Prepare for Impact! sumo wrestler.
A Poptropican found the crate and entered it to obtain a contaminated blueberry sample to create an antidote for the Zomberry epidemic. Big Blue attacked the Poptropican, but is stopped by the Camera flash which scares him off. Big Blue then exits the crate in fear. It is unknown what happened to him after this.