The Everton striker saluted his brace against India in a 4-0 triumph with his trademark corner-flag celebration, but then added a new telephone gesture.
He explained afterwards: 'It's about the devastation in Australia with the floods in Queensland.
'I donated a prize to the telephone-in, the link is on eBay, where two people get a chance to come and sit in a box from anywhere in the world and watch an Everton game, have some dinner and watch a training session, and have a signed pair of boots and jersey.
'I wanted to do something special and I got the phone-up to show the gesture because I want people to phone in on the telephone-in and donate money.
'I also want them to bid on my auction.
'This is football, but there is a lot more that goes on in the world than just football and if you can help families that are struggling. It is my way of showing that I care.'
This isn't the first time that Cahill has shown his support for world tragedies.
After scoring Everton's winner at BATE Borisov in 2009 he paid his respects to those who died in the tsunami tragedy in the South Pacific by making a paddle gesture.
The village from which Cahill's maternal family hail suffered tragically from the tsunami that lashed Samoa.