Where someone posts the phone number of an enemy on Gumtree.com under a false advertisment for something of value to many people at a below market price.
Dave: "Mate I've been gumtrolled! Someone posted and add for an iPhone 5s for 20 bucks!"
Lindorff: "Aww shit bro, the day your phone stops ringing will be the day you pass TAFE!"
Dave: "Shut the fuck up you seedy cunt, I'll gumtroll the shit out of you!"