give her one 

=have sex with her (British slang, coarse)

'You've been going out for ages! Haven't you given her one yet?'
'Out of ten, I'd give her one... hur! hur!'

give her one by MarkDallas July 21, 2007

I'd give her one 

Slang for inferring you want to shag a woman.

Look at that stunner! I'd give her one!

Or if you want to be clever:

That woman is beautiful.
Marks out of ten, I'd give her one.

I'd give her one by cs94njw February 8, 2017

Out of 10, i'd give her one 

Used when you happen upon a particularly beautiful woman, and then skillfully using the 1-10 scale as a rating - you twist it into a different type of ending - with the meaning that you would like to fuck this woman.

Me - 'Oooh, u see that?'
U - 'Uh huh, thats real nice!'
Me - 'Rating?'
U - ' Out of 10? ... I'd give her ONE!!'

Out of 10, i'd give her one by Hoki June 17, 2004