A tweet from Sen. Bernie Sanders to President Donald Trump on Saturday can only be surmised by the phrase “ooh burn.”

After Trump tweeted that his supporters should stage a rally and suggested that if they did, it would “be the biggest of them all,” Sanders issued a little reminder to the president.

“@realDonaldTrump They did. It wasn't.” Sanders tweeted about 1-1/2 hours later.

Accompanying Sanders’ message was a side-by-side comparison of what appears to be Trump’s inauguration and the Women’s March on D.C., an anti-Trump protest that took place the day after.

Many on Twitter were quick to pick up on Sanders' trolling: "Send in the bern unit, Bernie Sanders just poured the hot fire bern sauce all over Trump on Twitter," said Carlos Cuquejo.

In the days after his swearing-in ceremony, Trump blamed the media for underreporting the crowds at the event. The Trump administration went as far as to suggest the president drew the largest inauguration audience ever, despite photos that depict otherwise.

The National Parks Service, which runs the National Mall and Memorial Parks, declined to release an official crowd estimate for Trump's inauguration.