But one of the regulars in the channel is a girl!
Though this comic predates it, there is an Internet meme best stated as "there are no girls on the Internet." It is also known as Rule 16 or Rule 30 of the Internet. This comes partly from a supposition that girls aren't smart enough to go on the Internet or even use technology, and more directly from the idea that they are afraid of interacting in such a male-dominated subculture, so anyone claiming to be female on the Internet must be a guy pretending to be one for the purposes of active or passive trolling. Thankfully for humanity at large, the meme is now the opposite of true, but still lives on as a joke, albeit not always a pleasant one. For many users, the puerile nature of the Internet creates a repulsive force because of exactly what Cueball is doing. As soon as anyone claims to be a woman online, there will invariably be a slew of "tits or gtfo" replies.
Randall projects this stereotypical Internet douchebaggery onto Cueball, who behaves this way out of misogyny thinly disguised as a joke. This barely-a-joke, found in certain areas of the Internet (especially IRC and 4chan), holds the view that women are only "good for" sex and porn. By making such a huge deal out of her being a girl, he directs unwanted sexual attention at any woman who joins.
Black Hat, while usually a destructive force and self-proclaimed classhole, here switches positions with Cueball, standing up for women everywhere. (This makes sense when you consider that Black Hat tends to pursue Randall's thoughts in a more controversial way, see 86: Digital Rights Management). However, he still keeps some of his destructive tendencies and knocks down Cueball's door. He enlists the help of a Ponytail character named Joanna to ban Cueball from the Internet. (More than 9 years later, Joanna is hired to help Hillary Clinton win the 2016 United States presidential election in 1756: I'm With Her, released the day before that election. She is also shown in the 1000: 1000 Comics, where she is seen at number 653.)
IRC is the acronym for Internet Relay Chat. It is a protocol that eventually evolved into the instant messengers, chat rooms, and XMPP (formerly Jabber) servers around today. With the advent of live-streaming video online, IRC channels are making a come-back as a way for hosts and audiences to communicate with each other in real-time.
An EMP is an electromagnetic pulse that will disrupt electronics from functioning normally. An EMP is a short burst of electromagnetic energy. Small EMPs will disrupt electricity momentarily, while larger EMPs are capable of burning out circuitry and erasing hard drives.
At the title text, Cueball tries to defend his misogyny by claiming that one of his IRC chat system acquaintances is a girl, as if to imply that that makes his words no longer misogynist (this is similar to the defense "I'm not racist! Some of my best friends are black!").