Half secret code, half callback to the past. Lern at Glern's is a term that is still used to this day, albeit with less frequency and zero accuracy. Granted, back in the day it was also rarely used accurately. There were a scant few Lerns at Glern's even when the phrase was coined. Most of the memorable times at Glen's house were LANless. From lots of puking, to someone making out with a questionably pregnant girl, to a person sleeping in the "baby poo bathroom". There were good times at Glen's, even without a LAN set up with Diablo II. Any occassion at Glen's house would fall into the Lern at Glern's category.
Any occassion outside of Glen's house can also fall into the Lern at Glern category. Like most of the phrases used by the Inner Circle, Lern at Glern's is said ironically. Sometimes someone will say "Lern at Glern's!" in an excited manner, then proceed to hang out in the same location. There will most likely never be another Lern at Glern's, but 40 years from now everyone in the Inner Circle will know what it means.