Gives a hand

"Sure" she says. "Turn the other way, I'll have to reach round from behind."

You turn away from her and she moves behind you. She puts her arms round your waist and grips the tops of the jeans and begins to pull them together. You realise that you've been getting a little excited by the flirting and there is a definite bump in your jeans.

"They are pretty tight, maybe we'll need a bigger size."

You're a little relieved. The jeans are button fly and she would have noticed your hard on if she had tried to do them up.

"But let's try a little more with these ones first. They're meant to have a little stretch in them."

She reaches down and begins to do the buttons up one by one along the length of your cock till she reaches the top.

"There" she says "no problem. You might find them a little uncomfortable for a while, but we can do something about that if you want."

She giggles and blushes a little when you turn round.

You can tell she knows.