Yeah, I remember him and Sub being 6' or 6'2". He looks smaller because of optical illusion. With the way he's spread out, and his head is a bit bigger than Scorpion's as well. I remember putting the line art of The Joker in one piece, and it more or less matched up with Scorpion, his upper half was a just a bit wide was all.
And this started as a doodle on my plane ride to Mass. back in August. Just something to amuse myself. I liked it, so I did one of The Joker as well on the flight back, scanned them and then the rest was done in PS CS2.