observe Egyptian waterway
A.k.a., "See Nile"; this term refers to a "somewhat-out-of-it" older person's delusional fantasies, hallucinations, forgetfulness, and other indications/symptoms of his being "in la-la land".
True story --- yesterday I helped my elderly disabled friend wif his home-entertainment system, then gave him a ride to da local convenience store. While there, I observed another elderly dude wif a fancy late-'90's Lincoln Town Car, and spoke admiringly to him about da car. I then went and sat in my own car to wait for my aged friend to finish shopping. When he did re-emerge from da store a few minutes later, he chatted a bit and expressed admiration to da antique car's owner as he was on his own way into da store, then turned and got into da car's front passenger's seat and closed da door. Well, naturally, I assumed dat da car's owner had himself offered my friend a ride home, and so I tentatively went to confirm wif my friend dat he would no longer need a ride home from me. He looked a bit puzzled at my question, and then said dat no, he'd still thought dat I was gonna transport him back to his apartment. I actually had to (super-pleasantly and gently, of course, since it was obviously just a completely honest mistake) verbally point out to him dat he was in fact sitting in a different car --- "Well, ummmmm... MY car is over there... you're sitting in this OTHER man's car" --- before he finally "woke up" to da fact dat he was currently occupying da wrong vehicle. So as we were leaving, I smilingly joked wif my friend dat perhaps he had begun to "observe Egyptian waterway", as in, to become somewhat "see Nile". He took my gentle jocular ribbing in good humor.