birthday suit

plural birthday suits · alternative birthday-suit

1. humorousidiomaticoftenNakedness, unclothed skin; an exposure of a human's natural anatomy without clothing.

   George embarrassed his aunt by answering the door in his birthday suit.

   4 more examples

   Nature, the universal tailor, provides for every other animal a birthday suit of clothes which is to outlast his life; but man, though so peculiarly sensitive to the assaults of the elements, is ushered into this nether sphere without any covering, in order that he may be compelled to exert his faculties, and become his own tailor, and thereby his own civilizer.

   1842, H., “Short Rides in an Author's Omnibus”, in Thomas Hood, editor, The New Monthly Magazine and Humorist, page 267

   At last I'm down to the nitty-gritty, my original birthday suit. Where do I put my hands? I need pockets.

   1998, Paul Vaughn, “Confessions of a Naked Writer”, in Orange Coast, page 185

   The terms naturalistic and naturalism suffer from the fact that they have a range of meanings, covering a variety of things from the Romantic submission to nature or the collecting of butterflies to the practice of bathing on the beach clad only in one's birthday suit.

   2000, Denis Charles Phillips, The Expanded Social Scientist's Bestiary: A Guide to Fabled Threats to, and Defenses of, Naturalistic Social Science, page 85

   A person suddenly caught naked by the collapse of a building wall is treated quite differently than a person who intentionally “streaks” a public gathering in his or her birthday suit.

   2001, Tom Slattery, Immodest Proposals: Through the Pornographic Looking Glass, page 181

2. Used other than figuratively or idiomatically: see birthday, suit.