Peter Answers is a virtual tarot card reader website that is used as a prank. The person playing the prank can trick others into thinking that Peter is really answering their questions while they secretly type the answers in themselves.
Peter Answers appears to be a legitimate tarot card reading site where someone asks a question about their future and receives an answer. There are two boxes on the homepage: a "Petition" and "Question" box. "Peter, please answer the following question" must first be typed into the petition box, followed by a question. It then calculates and provides an answer.
The prank is done by typing the answer covertly into the Petition box. This is done by placing a period after Peter and a period after the answer, or the Petition - periods do not show up in the answer. The answer does not show up to other people, but is revealed as "Peter, please answer the following question."