tailgating
n.— «But she did not heed one warning: She left her door unlocked after returning from the party Dec. 12. Surveillance cameras show her entering Hill Hall shortly after 11 p.m. More than five hours later, the cameras filmed Taylor sneaking into the dormitory behind another student, a practice called “tailgating.” The cameras caught him leaving more than an hour and a half later, one of Laura’s gift bags in hand.» —“EMU slaying probe reopens wounds” by Joe Menard in Hastings Detroit News (Michigan) May 10, 2007. (source: Double-Tongued Dictionary)