Are you looking for any particular saying?
what about the Black Eyed Peas, Ba Bump...
or just the kids' chant: hands, knees and bump-sa-daisy?
Plus, people sometimes just type in 'Bump' to change the position of a post on a chat site such as this one...
being bumped from something
eg having booked your seat on a plane, when you arrive at the airport, they have given it to someone else and there is no room left.