bluejacking
From Longman Dictionary of Contemporary Englishbluejackingblue‧jack‧ing /ˈbluːdʒækɪŋ/ noun [uncountable] the practice of using a mobile phone with Bluetooth technology to send a text message to another person near you, without letting them know who has sent the message. This is usually done as a joke to surprise the person who receives the message. —bluejack verb [intransitive, transitive] —bluejacker noun [countable]