She decides to give it to Luffy, along with the mindset to use it.

Hancock considered the Note, and all she could do with it. Really, the only person she would want to use it on was Luffy, and he'd be going in two years... Then again, she could always make him stay with her... She genuinely considered the thought as she stared at the Note...

But... No... Luffy had already lost his brother, she couldn't take his dream from him too... But maybe she could give him so much more...

She took the pen, and began to write, "Monkey D. Luffy will gain an immense libido, and will understand and greatly enjoy sex. He will seek sexual pleasure at every opportunity when not pursuing his dream, and will recruit as many female members as possible on his crew. Boa Hancock will give Luffy the Sex Note tomorrow, and he will be able to use it without any spelling mistakes, and while he will never be cruel to anyone he uses it on, he will still use it as he desires to satisfy his new sex drive." She considered another moment, realizing this could interfere with his Haki training, and added, "Whenever he has sex, he will gain a slight increase in ability of the form of Haki he would have been training in during that time, 1.5 times as much as he would have gained." There, now it would actually benefit his gains in strength. "Silvers Reighley will do nothing to stop Luffy from pursuing his sexual desires or using the Sex Note."

She then sighed as she set the Note down and headed to bed.

...

The next morning, Luffy came again, and Hancock explained what it did before giving it to him.

He looked at the Note like it was a priceless treasure, which, frankly it was.