Tailgating meaning : To drive dangerously close behind another vehicle. To follow another person through access control on their access, rather than on one’s own credentials, especially when entering a door controlled by a card reader. (of a broker) To privately purchase or sell a security immediately after trading in the same security for a client. To have a tailgate party. The act of driving dangerously close behind another vehicle. A tailgate party (social event held on and around the open tailgate of a vehicle)