old hat

Short definition from Wiktionary

Noun

1. 1
   Something regarded as very familiar and unoriginal, hackneyed, or out of date.
2. 2
   The female genitalia.
3. 3
   A woman treated as a sexual partner.
4. 4
   Sexual intercourse.

Adjective

1. 1
   Very familiar and unoriginal; common, hackneyed, out of date.
2. 2
   Alternative form of old hat.