How to avoid/get away from a creeper at a con?
My best friend and I are going to Ohayocon in a few weeks, and we know for a fact that a certain guy we met at Sugoicon will be there also. He spent some time hanging out with us and it was glaringly obvious that he was rather attracted to my friend, but she thought he was just being nice so she didn't shy away from him. She doesn't want to tell him off for some reason, but she's dreading inevitably meeting him at Ohayo.
What are some (clever? XD) ways to try to get away from a creeper before notifying the proper authorities?