aramis erak
Legend
It's a reference that would have been lost on non-gamers at release. As others have pointed out.It's almost certainly a D&D-based reference. They were playing a pretty realistic (for teen boys) game of D&D in the movie, arguing about pizza and whether or not to let the younger brother play and ogling Elliott's mom (who had it goin' on long before Stacy's mom, at least relatively speaking). We caught the reference right away while watching it.
I was a D&D player/DM at the time, and I didn't get it. But I wasn't looking out for D&D references, either.
It's real easy, 40 years later, to say that D&D was in popular media and think that people might have recognized it... but most had no bleeding clue what D&D was. The point where it was becoming known was mere days away when ET released...
ET released 11 June 1982; Irving Pulling's suicide was the 9 June 1982, and over the next few weeks the start of the satanic panic would arise. Right during the run of the movie... and, in the US, D&D was starting to get a name with the public.