It’s the case of the sniffles heard around the country.

The small noises made by Donald Trump throughout the first presidential debate didn’t go unnoticed. Social media users and late-night comedians were quick to comment on the Republican nominee’s sniffles, many making comparisons to recent health concerns raised about his opponent, Hillary Clinton.

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Some Twitter users joked that Trump’s sniffles were the result of pneumonia, an obvious reference to the Democratic nominee’s recent bout with the illness. Several mock accounts were made dedicated to the topic.

Others, including Vermont Governor Howard Dean and The Late Show hostStephen Colbert, wondered aloud whether Trump was using illegal drugs.

“Notice Trump sniffing all the time. Coke user?” Dean tweeted, garnering over 20,000 retweets.

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During his monologue on Monday’s live show, Colbert joked that Trump “sounded like he was fighting off a cold…with cocaine.”

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After playing a montage of Trump sniffling, Colbert added, “He sounded like the coked-up best man in the bathroom at a wedding. ‘You guys, I got it, I know how we can fix the entire economy. Let’s buy a boat.'”

However, the 70-year-old business mogul blamed the noises on a faulty microphone that picked up his breathing.

“No, no sniffles. You know, the mic was very bad, but maybe it was good enough to hear breathing,” Trump said on Fox & Friends Tuesday morning. “But no sniffles. No cold.”

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Earlier on the Fox show, Trump even suggested that someone had purposely tampered with his microphone.