@ party

plural @ parties

1. InternethistoricalAn informal private party held as part of a convention, giving Internet users a chance to meet in person.

   Hi! An @ party will be held in Room 3121 at Balticon on Saturday night, starting at 10 PM and going for an as-yet undetermined while. The @ party is hosted by Digital Express Group, purveyors of that mightiest of refreshments, digital espresso!

   1992, Richard L. Butler, “An @ party at Balticon, Room 3121, hurrah...”, in rec.arts.sf.fandom (Usenet)

   1 more example

   I've been to a few @ parties- it's very simple. You look at the party board, and show up at the appropriate place and time. Usually/often someone at the door will ask you for your email address (just to make sure you aren't some kind of clueless geek, I guess), and you go on in and meet net.people.

   1993, Binky, “@ Party?”, in alt.fandom.cons (Usenet)