Yellow Hate Disease

The Yellow Hate Disease is a disease that appeared in the cartoon show episode "Hefty's Heart". Gargamel created the formula for spreading the disease called hate juice, which he used a flea that had ingested the hate juice to transmit. The infection causes its victim to have a yellow X on his arm, which at that point the normal behavior of that person would change to nothing but hate.

The first and only victim of that disease in the episode was Hefty, who normally loved doing things for his fellow Smurfs. However, the change in his behavior caused by the disease, not to mention his heart tattoo being replaced by a yellow X, made his fellow Smurfs concerned for him. Papa Smurf found out that the disease was contagious and had ordered every Smurf to stay in their house until he found a cure for it. Hefty refused to stay in his house and so chose to leave the village, where he was captured by Azrael and then brought to Gargamel, who used him as bait for the other Smurfs to come and rescue. Papa Smurf and four other Smurfs went with him to rescue Hefty, but were trapped onto a table top covered with glue. As Gargamel contemplated on what he was going to do with his captives, he first humiliated four of them before turning his attention on Papa Smurf, threatening to give him a shave. It was through seeing the village leader being threatened by Gargamel that Hefty had a change of heart and overcame the Yellow Hate Disease, rescuing Papa Smurf and his fellow Smurfs from the evil wizard.

In the EMPATH: The Luckiest Smurf story series, Hefty's contraction of the Yellow Hate Disease brought on the concern of Tapper, Duncan, and Tuffy, and almost resulted in an altercation with Duncan and Tuffy.