Upset Neighbor was a neighbor of Jack's. He was upset because Jack tried to kill his friends in the sewers.
He first appeared on Filthy Frank's TooDamnFilthy channel's video titled "WORLDS BIGGEST RAT??!! (DISGUSTING)." He was an awfully abnormal boiling kettle of a man that plowed his way through the walls of Jack's kitchen. He tries confronting the three queen-pieces of the chromosomal universe, only getting ridiculed by all of them. This was a very dark debut and departure for this camel-milking man of a few words.
- His gender is unspecified since only the waste-up of this man (if it even has a proper waist) was exposed in the video.
- He is affiliated with Jack. It is unknown why.
- He occupies his time fixing pipes in the sewers, where the two rats came from.
- It is speculated that he was one of the unnamed neighbors that were complaining about noise in Filthy Frank's apartment in his video titled "NOISE COMPLAINTS."