tailgating

/T EY1 L G EY0 T IH0 NG/
verb
  1. 1

    To drive dangerously close behind another vehicle.

    โ€œThat idiot has been tailgating me for the last five minutes.โ€

  2. 2

    To follow another person through access control on their access, rather than on oneโ€™s own credentials, especially when entering a door controlled by a card reader.

  3. 3

    (of a broker) To privately purchase or sell a security immediately after trading in the same security for a client.

  4. 4

    To have a tailgate party.

noun
  1. 1

    The act of driving dangerously close behind another vehicle.

  2. 2

    A tailgate party (social event held on and around the open tailgate of a vehicle)

Source: https://en.wiktionary.org/wiki/tailgate, https://en.wiktionary.org/wiki/tailgating