JessicaRulestheUniverse.com

TOKYO—Over the past few years, as many people rushed to trade in their old phones for smartphones, Japan’s philanderers have remained faithful to one particular brand: Fujitsu Ltd.’s older “F-Series” phones, which feature some attractive stealth privacy features.

The aging flip-phone—nicknamed the “uwaki keitai” or “infidelity phone”—owes its enduring popularity to customers who don’t believe newer smartphones are as discreet at hiding their illicit romances.

Read Japan’s Philanderers Stay Faithful to Their “Infidelity Phones” in WSJ

Here comes your Wi-Fe! If we spot someone with this flip-phone we’ll just assume he’s a cheater.