Letters that make in one's birthday suit
s, a, o, b, d, e, n, h, r, t, i, u, y are letters that make 'in one's birthday suit'
Words within in one's birthday suit
IT, ThD, birth, IR, DA, Day, day, one, on, in on, in, suit, IN, NE, birthday suit, Bi, In, Ir, Ne, Th, birthday are words within 'in one's birthday suit'