Be mysterious or eccentric for a day. Or flirt outrageously. And see who you attract.
If you need to do this at a costume party, that’s ok. Sometimes it is easier for folks to be outrageous or intriguing if they are wearing a mask. That’s ok.
The point is to take a spin at bringing out a different side of yourself.
Of course, if you are normally loud and obnoxious, you might try being very quiet or almost invisible. That can be fun, too. Whenever I try to do it, people think I’m angry. Hmmh?!