Police mistakenly believed it was a coded request for 10g of cocaine when they seized the supplier and his phone.
Dad-of-four Luke said officers threatened to throw him off a balcony unless he “told them where the drugs were”.
He and two friends were released in August by a judge due to a lack of evidence.
But prosecutors in the United Arab Emirates are appealing against the decision.
Luke, who spent £150,000 on legal fees, is now back home in Bishop’s Stortford, Herts.
In a message to Brits planning to visit the UAE, he said: “Don’t bother if you value your liberty.”
Pressure group Detained in Dubai said police there were behind “hundreds” of wrongful drug arrests.