Answer: Police Officers

Izzy Einstein and Moe Smith were the most successful Prohibition-era enforcement officers around. Officers in the federal U.S. Prohibition Unit, they were responsible for nearly 5,000 arrests between 1920 and 1925.

The secret of their success? Outright honesty. While they employed various costumes and ruses over the years, they had a surprising amount of success walking right up to speakeasies, and simply announcing they were police officers looking for a drink. Bouncers and bar tenders alike thought the whole thing was a gag; after all, what kind of detective would just walk right up and announce himself as such?

The two men were consistently complimented on how original the gag was and how authentic their badges looked. They’d order a round of drinks, take a sip, pour the rest into a clever funnel-and-bottle system hidden in their overcoats to serve as evidence, and slip out to drop the evidence off at the local station.