When Marco Rubio started talking about Donald Trump's hands, conversation really went below the belt at Thursday's Republican presidential debate.

"You know what they say about men with small hands," Rubio, a U.S. senator, told Trump during Fox News's debate. "You can't trust 'em."

Trump felt the need to correct him on that point.

"Look at those hands. Are these small hands? And …  if they're small, something else must be small. I guarantee you there's no problem," Trump said, showing his hands to the audience, assuring them that his hands were normal-sized, as was his "something else." 

It's an almost 30-year-old insult that Rubio and comedian John Oliver have revived in recent weeks.

In 1988, Spy Magazine's Graydon Carter called Donald Trump a "short-fingered vulgarian." To this day, Carter gets envelopes from time to time with photos on which Trump has circled his hand.

"See, not so short!" is usually written on the packages in gold sharpie, according to Carter, who said he recently replied to one saying "Actually, quite short."

The accuracy of the statement is in question, however.

"Trump is not a "short-fingered vulgarian," for the sole reason that he is not short-fingered," wrote Phillip Bump for the Washington Post, who did a size-relative photo analysis of Trump's digits

Seen against this entertainment reporter's hands, Trump's hands do appear roughly the same size.  

While comments from Rubio were deemed "nonsensical" by Justin Moyer of the Washington Post, some thought that the Republican front-runner's response to a genitalia insult demonstrated a thin skin.

"So it would seem that not only is Trump a liar, a bigot, a misogynist and a greedy power-hungry manipulator. He also has a fragile masculinity as well," wrote Gideon Resnick for the Daily Beast

Many more seemed concerned, or highly amused, about the discourse of the Republican debate.