Watch | Donald Trump defends penis size during Republican debate

The tone of the Republican debate reached incredible new lows last night, as Donald Trump used the latest event to boast about the size of his penis. Arguing about the levels of personal attacks between the candidates, Florida Senator Marco Rubio said: "If there's anyone who has ever deserved to be attacked that way, it's Donald Trump, for the way he's treated people throughout this campaign." "I have to say this, he hit my hands," Trump responded, referencing Rubio's comments last week that the billionaire businessman has unusually small hands (and what that may imply about his other, erm other body parts). "Nobody has ever hit my hands, I've never heard of this." "Look at those hands. Are they small hands?" he asked the audience. "And he referred to my hands saying, if they're small, something else must be small. I guarantee you there's no problem. I guarantee." His comments drew an expected round of laughter from the Fox News audience. The claim will bring delight to a new parody Twitter account 'Twinks 4 Trump' which hails Trump as the ultimate daddy. Later in the debate, the pair traded more insults, with Trump referring to 'Little Marco' and Rubio referring to 'Big Donald'. On a day when Republican veterans Mitt Romney and John McCain both begged the party to turn away from Trump, the madness of the 'big hands, big penis' exchange wasn't lost on the viewing American public. Rubio is currently trailing a distant third in the Republican contest, behind front-runner Trump and Texan Senator Ted Cruz, who is seen as the only chance to scupper The Apprentice USA star's Oval Office dreams. Rubio meanwhile, is coming under increasing pressure to pull out of the race in order to galvanise more anti-Trump support behind Cruz. More stories Twinks 4 Trump account hails the ultimate political daddy Donald Trump gay erotica novel takes Amazon charts by storm