Birthday Tux
Similar to a birthday suit, a birthday tux is one's naked form but polished up for fancier events for which a birthday suit would be inappropriate. A birthday tux is more well trimmed and tanner than a birthday suit.
Valerie: "Are you wearing your birthday suit to the orgy?"
Michelle: "Are you kidding? I'm wearing my birthday tux! I'm going to shine like a diamond!"
Michelle: "Are you kidding? I'm wearing my birthday tux! I'm going to shine like a diamond!"