A Blonde and a cell phone

A young man wanted to get his beautiful blonde wife something nice for their first wedding anniversary. So he decided to buy her a cell phone. She was all excited, she loved her phone. He showed her and explained to her all the features on the phone.

The next day the blonde went shopping. Her phone rang and it's her husband, "Hi hun," he said "how do you like your new phone?"

She replied "I just love it, it's so small and your voice is clear as a bell but there's one thing I don't understand though."

"What's that, baby?" asked the husband.

"How did you know I was at Wal- Mart?"