From my experiences as a Channel Op in IRC the largest reason that guys do this is to cyber. Here is an example of what happens many times in a night.

**HugeCock enters the room**
HugeCock: Any girls want to cyber?
**silence**
HugeCock: Any girls want to cyber?
**silence**
**BiAmy enters the room**
BiAmy: Any bicurious girls want to chat privately?
**HugeCock leaves the room**
**SaraBi enters the room, Has entered before as HugeCock**

That is usually how it goes. Guy comes in looking to cyber and gets shut down by the actual women there. He then notices that there is a Bi "girl" looking for some action. He then leaves and comes back with a bi girl name of his own. Unknown to him this other girl is actually a guy. So what you end up getting are two guys pretending to be bigirls with each other to get their nuts off.

And yes I have a program that lets me know if somebody leaves, changes their name, and then comes back.

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