...you hear "Hey old fart!" turn to look, and see they were talking to someone else. Someone younger.
You politely greet someone and introduce yourself, only to hear the person say "Got some ID on that?" (Course if that happens to me, I'll simply say,"Yes I do, but I'm not showing you-you're just gonna have to trust me, BUDDEH!"
I used to get that from an x-girlfriend, but she'd ask me that same question when it took 2 or more rings for me to answer.