I dunno. You could attempt Xombie, but I doubt a stylish Xombie-like Madness character would be very easy to make. Foamy is also a possibility, even if quite a few people would hate you for it. My other thoughts are Alien Hominid, Johnny Rocketfingers, Dad's Home, and maybe some form of a Madness sprite movie.
Senti
Brackenwood: <a href="http://www.newgrounds.com/collection/brackenwood">http://www.newgrounds.com/collection/
brackenwood</a>
No Voice acting and lovely animation.
Salad Fingers: <a href="http://www.newgrounds.com/collection/saladfingers">http://www.newgrounds.com/collection/
saladfingers</a>
Unfortunately some voice acting...but it isn't necassary.
Tankmen: <a href="http://www.newgrounds.com/collection/tankmen">http://www.newgrounds.com/collection/
tankmen</a>
The every popular tankmen...but, it's got voice acting...
Xiao Xiao: <a href="http://www.newgrounds.com/collection/xiaoxiao">http://www.newgrounds.com/collection/
xiaoxiao</a>
Stick fun...but only if you can animate like this guy can...other wise it'll look like any other stick movie.
Good luck!
swiftstylerX
Brackenwood has been a possibility for awhile now... But I don't think I could live up to his animation skills.
Salad Fingers is also a possibility.
Tankmen is a no-go... It wouldn't be very funny unless it had voice acting.
Xiao Xiao is also a no-go, I do not want to animate sticks, and it would be quite impossible to have a Madness character as a stick figure. lol