The Joker is highly egotistical and for all his vaunted sense of humor cannot take a joke at his expense. To make an example of hacks printing scurrilous lies about him (even though they were actually all true) he kidnapped Ryder and dropped him into an entire vat of Joker Venom, which he then intended to pump into the offices of several major Gotham newspapers. Saturation by such a quantity though had a different effect to what the Joker expected. Rather than dying Jack Ryder's body went into overdrive and he burst out of the tank transformed as the Joker had been, but far more so. He was now superstrong, super agile and his body healed from any wound at a hyper-accelerated rate. He leapt madly about and trashed the Joker's chemical plant and all his goons before leaping off across the city.