Not sure why I just taught everyone to flawlessly impersonate me to pretty much anyone I know. Just remember to constantly bring up how cool it is that birds are dinosaurs and you'll be set.
Cueball lost the server password and is asking Megan what it is. Megan correctly comments that she can't be sure through text-based messages that it's really Cueball asking for the password; it could be someone impersonating him attempting to socially engineer access to the server. Cueball answers by starting to develop a cryptographic protocol they can use for proof of identity, probably something like OTR Messaging as implemented in many XMPP chat clients or Feige–Fiat–Shamir identification scheme. In reality, it would already be too late for that — they should have prepared something beforehand. Before he even finishes, Megan answers "It's you", meaning that no one else is so geeky that they would answer like that. Cueball, dismayed at the fact that his geekery has become a defining characteristic of his and also at a lost opportunity to devise his protocol, shouts [texts?] "NO!".
In the title text, Randall suggests that this is, in fact, his own personality, and that anyone reading the comic can now impersonate him. For a bonus, he notes his own fascination with the fact that birds are just modern dinosaurs, which one could use to impersonate him as well.