The Joker committed crimes with his comedic weapons which included his famous acid-spewing flower that was always tucked into his lapel. The infamous flower that the Joker wore in his lapel sprayed (at any given time) acid, poisonous laughing gas, water, knock out gas, or nothing at all. The flower's colors varied over the years, but were usually yellow or purple.
Live-action Batman series
The Joker wore a flower that didn't spray acid, but was still deadly. It sprayed water, powder, and knock out gas.
Warner Brothers Batman film
- "Have a little whiff of my posy."
- ―The Joker to Vicki Vale.[src]
In the 1989 film, Batman, The Joker referred to his acid flower as his 'very special flower' and removed it from his suit lapel to give to Vicki Vale. The flower looked too large and too shiny, like plastic, which Vicki noted. The Joker then squeezed the flower, which squirted out the lethal acid that was contained within. Vicki dodged, and the Joker replaced the flower in his lapel. He also used it toward the end of the film, to melt the seal the held the bell to the Bell Tower at the Gotham Cathedral to make the huge heavy bell plummet on Batman who still went up the stairs, The plan failed as it just barely missed Batman, and only caused massive damage to the Cathedral's stairs. However it did, intentional or not, halt the GCPD from going up the stairs.
The Joker stunning Batman with a blast of water from his lapel flower.
Batman: The Animated Series
In the Season 2 episode Harley and Ivy from Batman: The Animated Series, the Joker first used the flower in his lapel to spray laughing gas at Poison Ivy. However, Ivy simply laughed, and told him the gas would not work on her (because of her immunity to poisons), much to Joker's surprise. She retaliated by dealing Joker a savage karate kick to his crotch that was hard enough to temporarily alter the pitch of his voice.
The Joker later used the flower in his lapel to spray laughing gas on his victims in several other episodes in the series.
The New Batman Adventures
In The New Batman Adventures, the Joker used the lapel flower once to spray laughing gas, and another time was able to defeat Superman with it. The Joker, during a battle with Superman, tried to use Kryptonite on him, who had come prepared with a lead suit. However, a dismayed Joker soon remembered the flower in his lapel. Joker squirted green acid from his lapel flower all over Superman, which destroyed his lead suit and allowed for Joker to gleefully shock him with his Joy Buzzer, as Superman was exposed to the Kryptonite.