Someone who is seemingly emotionless in person, but always posts online with a lot of excitement (a lot of exclamation marks, all caps, etc.)
Jennifer, being very internetaverted, sat quietly in Starbucks, eyes glued to her phone, without so much as a polite smile on her face while posting to Facebook, "OMG!!! HE PROPOSED TO ME!!! I'M GETTING MARRIED, EVERYBODY!!!!!! AAAAAAAAHHHHH!!!!!!!!"
Having successfully completed a session of doing whatever you wanted on the internet.
Present tense is "interwebbing", the act of currently being online and fulfilling your online needs.
Derived from "interwebs", which may have came from "interweb", as well as "internets", which was obviously from "internet".
After having checked my email/myspace/rvb/facebook/news/<insert other regular online activity here>, I felt well-interwebbed as I quit <insert browser name here>.
"The interwaves are not something you dump something on. Its not a truck. Its a series of invisible tubes that connect your Personal Internet to the Internet."