One important question was engrossing social media on Thursday: did Bill Shorten get called a "grub" or a "c---?"

Viewers will have to make up their own minds after watching, and perhaps pausing and rewinding, footage of Question Time from Wednesday afternoon, when Education Minister Christopher Pyne was captured on camera hurling a four-letter insult at the Opposition Leader.

But what exactly was his slur of choice?

In the footage, Mr Pyne is shown at the dispatch box delivering a tirade at Mr Shorten.