Brazilian brothers named Hulk and Conan inject themselves with dangerous chemicals to create 28-INCH biceps Two Brazilian brothers with biceps measuring more than 25 inches have revealed the secret to their incredible size - regular chemical injections. Tony 'Hulk' Geraldo , 49, and Alvaro 'Conan' Pereira, 50, have both been injecting dangerous chemicals since their teens to make them as big as possible. The brothers, from Rio de Janeriro, Brazil, claim there was a time when they were 'addicted to getting big' but now believe they have it under control. Mr Pereira has been injecting his biceps and legs with a supplement called Potenay B12 on and off since he was 15 years old. The brothers inject the chemical in cycles - two times a week with five days in between. The bodybuilders' doctor has recently insisted they stop injecting for health reasons, and because their skin cannot stretch anymore. Potenay B12 should only be used for veterinary purposes, on animals such as horses. But Brazil has seen an increase in people injecting the supplement to get bigger, quicker.