Rofl. I tend to pay for some things, like I went out to dinner last night, she paid for her meal and I paid for mine, and then the drinks etc.
The other thing I do is find good discounts on things. For example I can get really cheap movie tickets, or half price "gold" (private cinema, 30peeps, recliners, waiters, alcohol etc) tickets which makes for a fun night out. Overall you dont need to pay for everything, it makes you look like your trying to buy them out.
Errgh! Don't go to Roppongi!!