N.W.,
Just being there is weird enough =)
But you want to spike your punch eh?
It's gonna cost ya' remember that..
Check out this site:
http://www3.tky.3web.ne.jp/~edjacob/intro.htm
http://www.quirkyjapan.or.tv/
Or arrange a "Go-kan" that should be a very funny affair ( a group blind date). Japanese actually do this as a way to meet a possible girlfriend/boyfriends.
Japanese love tours and the Major tour companies have all kinds of "special tours", ninja tours, geisha tours, etc.
http://www.japantravelinfo.com/
http://www.japantravelinfo.com/press/upcoming_news_09.html
In Tokyo, check out Akihabara area for its electronics and anime ----but "more importantly" where it is actually cool to be a "nerd and otaku" now!! The Densha Otoko drama had the effect on Japan to the extent that girls are now searching for nerdy guys! (what a laugh when I found that out).
Go to Shinjuku and check out a Kabuki play or just walk around and amaze yourself with all of the humanity of Shibuya near Hachiko station. Or feel at home in Roppongi with all of the worlds worst gaijin hangout ..j/k
Got to go to Harajuku and see all of the weird fashion (But, you've been to these place before right??)
But everyone does that stuff.. Hmmm.. Okay,,,
Off the beaten track:
One of my favorite places is Yokohama. I used to live there actually for 3 years. It is not too far from Tokyo (35 min. by express train) and you could go to Minato Mirai within walking (winding) distance from behind Yokohama station (15 min) OR easier take the Nigishi-sen (line) to Sakuragicho station if you figure out the train schematic, it will take you directly there. It is very nice to get out and walk around, but it will be cold. You might want to take a taxi if you leave Yokohama station to get there.
There is also near Yokohama station the "Tomorrow" restaurant (near the YMCA) that specializes in garlic dishes. They serve humongous servings of everything even by American standards. It is a small place so being there right at 6PM is a must for groups larger than 2! But great food.
From Yokohama station get on a train to Kamakura for a day.
Also, Kamakura is a very nice place. It is very similar to Kyoto, with not so many temples. Go and see the Giant Buddha! It is about 20-30 minutes is also a nice place actually.
I've lived also in Osaka for around 3 years, but most of the strange things are located in and around "Doton-buri" area (Dotonburi bridge is famous for Japanes guys standing around and trying to pick up girls)This area's general location is called Minanmi-ku (south side), but check out American Mura (village)and Shinsaibashi, Ebisu, areas are lively and entertaining they are also adjacent to Doton-buri area.
Go to the "Pig and Whistle" in Osaka for a beer or/and some fish and chips (very British Pub style). You can find some people that speak English very well (and some gaikokujin too!) It is a very friendly and a good place to ask questions about Osaka. If you bump into the owner (Mori-san), tell him that I said Hello. I was an infamously good customer.
And since it is so cold, why don't you go up to Hokkaido island and have some great food, see the ice festival (sculptures, etc.) and take in some great skiing! But it is expensive to get there.
If you don't ski, go to a lodge and sit in an Onsen (hot bath) It is great to go to an onsen during the winter.
And last but not least, man you have to absolutely go to a "love hotel".
http://www.japanvisitor.com/jc/lh.html
http://www.links.net/vita/trip/japan/lodging/lovehotel/
I'd do that first, although it may be weird if you go with only a guy!! But great after a long night of partying.
I mean those love hotels have many motifs within the same confines and you can stay a few hours or a night.. it depends. They have plenty of them all over Japan.
Good luck!