We're going back to the concept of 'Engrish' that we were talking about earlier on with this one, and it's the worst example of all of them! If we read between the lines a little here, this is one of those shirts which is intended to be a boast on behalf of the person wearing it. She's basically saying that she's very good looking, and she could spend a fun time with your boyfriend if she chose to do so.
Unfortunately for her, whoever translated the phrase she wanted into English didn't quite get it right. Now, it reads like she's either seen your boyfriend and thinks he was nice, or your boyfriend has seen something nice. It's nearly there with the meaning, but not quite. We'd feel sorry for her, but as the intention of the shirt was to be smug and vain, we have no sympathy.