An exclamation which is to be used when somebody:
1. humiliates him or herself, or
2. fails to complete a task in a spectacular, yet comical, manner.
Derived from an ex-Rangers football (soccer) player, Filip Sebo, who was an utter failure with 'ra Gers in his only season with the team.
1. A man rides his bike down the street and he fails to see the curb ahead of him. The bike slams into the curb and the man is thrown off the bike. If you are on a car and spot the incident, be sure to yell "Seeebooo! Seeebooo!" at the man.
2. You are at the beach. You and a group of friends are tossing and punching a beach ball up in the air, when one of them swings and completely misses the ball, resulting in the ball hitting the ground. This is the perfect spot to yell out "Seeebooo! Seeebooo!" at the said friend.
(Particularly effective when the person at the end of "Sebo" is in no position to say anything against it.)