Daniel Keogh, the ABC's Science Show producer, was caught by surprise when he calculated that he owed the charity beyondblue more than $17,000 after pledging to donate $5 for every time an online message of his was "retweeted" on Twitter.

Keogh last Friday tweeted on his @professorfunk Twitter account that he would donate $5 to beyondblue for every time a tweet of his was retweeted by 10pm that night – but he didn't expect the message to be retweeted more than 3000 times.

The tweet and the ammount that Keogh needed to pay.

After doing the calculations, Keogh found that he owed beyondblue, an organisation that provides information about depression to consumers, carers and health professionals, $17,175.

Speaking with this website, Keogh said that he had become "a bit of a Twitter addict" and seeing as though it was his second year on the social networking site, he would celebrate by doing "something quite charitable".