I'd change colour too [when hot] if someone stole my man.
Dolly Parton - Caffeine, Caffeine, Caffeeeeeeeine (To the tune of Jolene) Color Changing Mug - Reveals Secret Message w/ Hot Water.
The mug starts out a glossy black color. When hot liquid is added the brilliant color message appears and the mug turns white! Surprise your friend with a secret message.