One of my contacts on Windows Live Messenger (MSN) had a .pif file virus. Here's how it went.
I'm just sitting in front of my computer when one of my contacts suddenly pipes up and says something about a Photo Album. He then attempts to send me this Zipped "photo album". I open it, and inside is a file called "Photo Album". Strange, I thought. It had the "Unknown file type" Icon. To the naked eye this didn't even seem like a photo album, but, I don't know about you guys, but most users will double click almost anything sent from an MSN Contact whom they know fairly well. But I right clicked and read the full file name. "Photo Album.pif". I almost instantly told the contact that he just sent me a virus. He insisted he had done nothing, but as he spoke to other contacts, they said that he was sending them something. He started saying "are u a hacker" and whatnot, and I reassured him that it was a virus and he was sending it to other people. Then I realised, "It must be taking over his computer" and directed him onto some articles about .pif file virii. I told him to get offline, run some virus scanners and fully eleminate the virus.
Later, he came back online and told me how he got the virus.
He opened "Miniskirt naked.jpg.pif".
Moral of the story? Don't open .pif files!