Scent of a Wookiee is a cologne that Homer owned. It is from the Star Wars collection of cologne and features Chewbacca on the front.
Homer put it in the safe along with other precious items from other members of the Simpson family. Inside the safe, the headlights on Lisa's Malibu Stacy car caused it to boil and explode.
Scent of a Wookiee is a reference to the Wookiees, large hairy aliens in Star Wars.