"It's a beast." Jennifer Connelly proudly shows off vagina wig.

Some actors gain weight for a role and some gain a wig for their vagina.

Oscar winner Jennifer Connelly has spoken candidly about the merkin she had custom-made for a nude scene in her upcoming film American Pastoral.

Connelly plays a 1960’s woman who wouldn’t have had access to a home-waxing kit or brazilian deals on Groupon. Tragic.

The 45-year-old explained what a “merkin” was to the studio audience.

“For those of you who don’t know what it is, and frankly why would you know what it is, it’s a vagina wig, basically,” she said.

Connelly told Jimmy Kimmel the wig came up after makeup artist Judy Chen questioned whether her downstairs grooming was “reflective of the era”.

It was not.

Kimmel held up an image of the wig that captured it in all its hairy glory.

"It's a beast!" She said.

The custom-made lady garden came after the actress was taken into her trailer and fitted with "training paper and a sharpie".

A wigmaker was sent the pattern and soon the merkin or "beast" was created.

American Pastoral is a drama set in 1968 that follows the story of one man's struggles to control his daughter after she adopts a new set of political beliefs.

The film is based off the 1997 Philip Roth Pulitzer Prize-winning novel of the same name.

It is set to be released in American cinemas on October 21 with no Australian date confirmed.

Feature Image via Jimmy Kimmel/ABC.