This is seen mainly in Xbox gamertags. People will make a gamertag such as xXxLeGiTsNiPeRxXx, which has rotating caps. This is basically when there is a word or phrase that alternates between lowercase and uppercase letters.
Jeff: Hey add me on Xbox Live
John: Alright, what's your gamertag?
John: ... are you serious...
John: You have rotating caps in your gamertag...
Jeff: 1v1 me!