A man and a woman went to the beach one day. There, they saw a teenage girl walking up to people and talking to them. Some replied heatedly, and some took what she had to give. The man and the woman suspected that she was selling drugs, so they decided to take it to the police. But when they were about to do so, the woman discovered that the girl only walked up to people with electric supplies. So the next time they went to the beach, they brought a boom box along. The woman went swimming, and the girl walked up to the man.
What did she sell?