Oh, we call it pulling names. Put everyone's name in a hat or bowl, then, everyone pulls a name out of the hat/bowl. Nobody tells whose name they have. Set the cost of the gift, say 5 dollars. Set the date for the exchange. Then let the fun begin. Everyone wonders who it is that has their name. It is fun if your co-workers can keep their mouths closed about whose name they have, but most can't and leaks happen, but it is all in fun. Usually you can figure it out because the person who has your name starts to pay attention to your likes and dislikes.