Sun bathing with Millie

I notice that Millie is looking at me through the corner of her eye, with a small amused smile on her face that she is not bothering to hide.

She stays like that for a while, pretending to flip through the pages of her magazine, and I am doing my best not to stare at her big tits so that my cock does not grow hard again suddenly.

After a while, Millie puts down her magazine, and grabs a bottle of sun tan lotion from the table next to her. She starts putting lotion on her big tits, really massaging it in, saying:

"I need to make sure I don't burn these two big bobcats in the sun."

I do my best not to look, but knowing that Millie is next to me rubbing lotion on her big tits is enough for my dick to grow rock hard again.

Millie notices this, and with a laugh says:

"Sorry Matt, I know this must be 'hard' on you, but I don't want the sun to burn my breasts."

Then she laughs at her own joke, and picks up her magazine again.

I want to say something, but what?