get boots and 4 pairs of double swords. alpha strike at team fights. atk speed let me over run. im the highlander n00b dont you know theres only one? ill backdoor your towers all day, watch them get chunked. hope your team shows up to play, and watch them get dunked!
Anywho, I'm a big fan of AD Twisted Fate. I find I can make lots of good plays with him, where AP wouldn't really be able to do much. Also, if I go mid with TF and I'm counterpicked with Galio, I just build full AD instead and laugh in his face.
Hybrid Diana turns a few heads too, but it's very strong. She plays scarily like Jax when she has the right items.
AD Akali, in the same vain, is a pain to deal with. You protect yourself from her burst thinking she'll kill you instantly, but then she stays on your face autoing you to death. Very trollish.
Full AP Skarner. Not exactly viable, but probably the funnest way to play him. His shield is Godly, and his E's damage and heal are also Godly.
Again not so viable, but Leona's a fun AD on Murderbridge and Dominion.
Teemo built fulltank is actually really frustrating to play as, because you have zero damage on a champ you're used to shredding people with, but it angers your enemies just as much.