Why did Mr. J throw Jack Ryder into the vat?

[BWDK]

I don't understand why the Joker did it, did he intend to create a second Joker-type human or did he just want kill Ryder? Did the Joker think he's the only one who could survive a bath in that toxic waste and get these "charming" looks?

As far as I remember the Joker's appearence is due to an allergic reaction right?

[Flying Grayson]

Off the top of my head I think that the Joker was pissed.
He's a pscotic killer. In the comics he killed Jason Todd and crippled the original Batgirl.

[James Harvey]

The joker threw in Ryder as...a joke. That, and he's nuts. As for the whole allergic reaction thing, the Joker was never allergic to those chemicals. Although, if you read The Batman & Robin Adventures Annual #2, Auther Reeves was allergic to Joker's chemicals, which caused the same reaction. The Joker chucked in ol' Ryder as a joke. Nothing more. Pretty mean joke, though.

[The Mad Hatter]

Why does the Joker do anything? The guy's nuts, and will do what it takes to cause pain he can laugh at. He had no idea the chemical cocktail would bring rise to the Creeper.

[EarthX]

I figured it was a bit to tantalize the old fans that they may have just created the Creeper (a.k.a. Jack Ryder in the comics). He's got that green hair too, but with yellow skin.

[The Mad Hatter]

Well, if you're looking for the behind-the-scenes answer, you're right. The artists kept drawing the Creeper in many different ways, but he still vaguely looked like the Joker. So then they figured, what if it's okay that he looks like the Joker, since the Joker created him? They had said before that they couldn't do Creeper's comic book origin justice without a two part episode (like they wanted to in B:TAS).