Long Line

At a store, a teenage girl stood in line waiting to pay for her items. Three people stood before her in the line. She took out her phone and checked all of her social media accounts, took some selfies and texted a few friends. After 15 minutes she realized that the line wasn’t moving at all.
She shouted at the cashier, “Hey dude, is this line going to take all day long?”
The cashier replied, “Please step aside miss and come here. You are standing behind three mannequins.”