...You go down to the hotel lobby at 5:00 PM to meet your crew for dinner and can't remember what they look like.
...After 4 nights of hub-turning you look into the mirror and see Moses.
...You can't tell the difference between the coffee stains and the hydraulic/ oil stains on your shirt.
...ATC clears you to a waypoint and you have to say "Unable, we're not RNAV equipped" and the controller replies; "I didn't know anyone still flew 727s."