Prank Calls are a joke done over the phone, usually towards the second party in a phone call. Ghost has been known to do prank calls to various parties.
Most of Ghost's prank calls are done on failtrolls who call and attempt to troll him (for example people who call up and say "Wanna fight, faggot?", or extremely racist propoganda, or who consistently fail multiple times in a show). Ghost makes a list of their phone numbers and on special occasions he prank calls them live on the True Capitalist Radio Broadcast.
His most recent series of prank calls was done on the 2011 Christmas Eve broadcast
Ghost's most famous prank call (Which he has repeated on numerous occasions) consists of him calling on the unsuspecting person and claiming to have "just been called by this number" and that someone threatened to kill his Grandmother. Another famous call was made to Caller 417, whose mother picked up the line on late Christmas Eve, effectively embarrising the creator of 'Robert Chomsky', and causing him to stop calling afterwards.
Unfortunately for Ghost, by 2012, the trolls had smartened up to his shenanigans commited on Christmas. With Amy Daly's help, who created a soundboard containing a large number of Ghost quotes, they began calling other radio shows on BlogTalkRadio, ranging from religious services, to enraged African Americans. Ghost has not taken amusement from this, and reacted in extreme rage after hearing a call to Howard Stern, along with calls by well known troll Cipher11 to schools, and businesses. Spermy the Cat was known to call shows with the soundboard back in 2011, resulting in many angry show hosts calling in out of nowhere, annoying Ghost greatly.