it's simple. just post a name (and a pic if you want) of a celebrity that starts with the first letter of the previous celebrity's last name. For example, if i post "Clint Eastwood" the next person starts their celebrity's first name with an E.
I'll start it off with olivia Munn
http://www.beertripper.com/OffTopic/g4/Olivia-Munn-Black_Dress_Hard_Rock.jpg