a bit of fluff

(Also a bit of skirt.) A sexually attractive woman.

Example:

I saw him yesterday with a bit of fluff.

be better than sex

said about something which is very enjoyable or exciting.

Example:

Riding a horse is a real fun. It's better than sex.

facts of life

the details about sex and reproduction.

Example:

His parents told him the facts of life when he was ten years old.

have the hots for someone

To be strongly sexually attracted to someone.

Example:

He has the hots for her but he can't tell her. He's so shy.

in the family way

(also in a family way) pregnant.

Example:

I've heard that Leila is in the family way. Is that true?

meat and two veg

The male genitals.

Example:

Everybody could see his meat and two veg because his trousers were so tight.

play away from home

to be unfaithful; to have sex with someone who is not your usual partner.

Example:

She stuck on her decision to divorce because she discoverd her husband playing away from home.

play the field

to have many sexual relationships.

Example:

He's not the kind of person to think of getting married. He's quite happy to play the field.

shotgun marriage

(also shotgun wedding) when the bridegroom is forced to marry the bride he made her pregnant.

Example:

It was a shotgun marriage. Nancy was three months pregnant when she married John.

virgin territory

a territory that hasn't been touched orexplored.

Example:

There is no sign of humans in that island. It's a virgin territory.

X-rated

not suitable for children.

Example:

Children ae not allowed to watch this film. It's X-rated.