"We have some bad hombres here and we're going to get them out."

With one line about immigration and his plan to remove drug lords from the United States, Mr Donald Trump inadvertently launched a Twitter hashtag that has been overtaken by tweets mocking the US presidential candidate.

Quickly, the hashtag #BadHombres began trending worldwide, with more than 31,000 tweets posted within the hour.

The Twitter account belonging to Mr Trump's opponent, Mrs Hillary Clinton, was quick to respond with a short and sweet "Hombres?". The word means "men" in Spanish.

Twitter users chipped in, turning the phrase around on Mr Trump and commenting on its unsuitability for an event as serious as a US presidential debate.

Just as at the previous presidential debates, the staffers working on the Twitter accounts of both candidates were extremely active, reacting to the goings-on onstage.

Searches for the word "bigly" spiked on Google after the debate started, but it is unclear if Mr Trump is actually saying "bigly" or "big league", as his Twitter account has used the hashtag #BigLeagueTruth liberally.