Abruptly moving someone out of the way of what they are after and rightfully deserve. This can be done by physically pushing the person out of the way, or by going behind there back in an underhanded fashion. Often times this is unexpected by the other person. The person does this either because they need what the other person is after or they just don't want the other person to have it.
1. Man that guy totally bull guarded his way to the front of the line!!