Rainyday.... I have a similar story..... it's not mine but it's about my aunt..... we were standing in the checkout line as well and the guy right in front of us (Caucasian) was taking his time and my aunt got mad and said "kutta badmash kitni dhair lagara hai" and he turned around and said " mujhe urdu aati hai" and told us that he lived in Pakistan for a couple of years...... my aunt was soooo embarrassed that she just left without saying anything! and I had to apologize on her behalf!