Policia Nacional, as they are known in Spain, responded to a tweet by culture journal Jotdown Magazine in which they asked "If you're travelling abroad (to EU countries) and you’re carrying four joints, is it better to have them on you or in the bag you check in?"
"It's better if you've already rolled them and hide them somewhere where the sniffer dogs don't detect them," Spain's National Police Force tweeted back.
They even provided a suitable place to hide them: "cigarette packet maybe?"
Even though the Policia Nacional's social media team rounded off the tweet by saying "you still risk a penalty for public consumption", the message caused a Twitter storm and won them even more followers.
Police soon removed the humorous 'advisory' messages and sent out a new tweet saying: "To avoid any confusion: possession and consumption of drugs in public places does result in fines."
But it's precisely this down-to-earth and friendly attitude on social media that has won Spain's National Police Force many new fans and led the country's media to applaud their innovative tactics.
Their light-hearted language and regular replies on Facebook and Twitter have proven key to engaging Spaniards of all ages in citizen crime fighting campaigns.
Recently, a murderer was arrested just 12 hours after the National Police Corps sent out a tweet with a photo and description of the suspect.
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Their feed warns the public of new scams and enlists the help of Spaniards, tweeting requests for information about drug dealers and other criminals, to be sent anonymously to a police e-mail address.
Police say they arrested 300 suspected drug traffickers from January 2012 to June 2013 thanks to information provided by Twitter users in response to these appeals for help.
"We try not to be very boring or too institutional or else people lose interest," Carlos Fernández Guerra, the force's social media manager, told news agency AFP in 2013.