Girl 1: I can't do that.
Girl 2: Do what?
Girl 1: What you're doing.
Girl 2: What? Drinking and walking at the same time?
Girl 1: Yeah. How do you do that?
Girl 2: I don't know .. I just suck on the straw and walk.
Girl 1: Can you show me how?
At this point, I just shook my head and walked away.
(It probably wouldn't have seemed as weird if it was two little girls, but these two were about 16 years old .. and no, they weren't blonde!)