Mariah was in New York on Thursday, ahead of the Halloween day, wearing a fireman's jacket which barely covered her jewelry-clad underwear, suspenders and stockings.
The "Touch My Body" singer was with her husband, Nick Cannon, who also donned a firefighter disguise - though he also had the T-shirt and trousers to match.
The couple had a pre-Halloween party which also coincided with their six-month wedding anniversary. To celebrate, they had a party and invited close friends.
To make their grand entrance even more interesting, the couple pulled up in the back of a fire truck.