She just had to do it.

Sit on my lap.

There were plenty of seats available at the party, all of which she ignored.

She never spoke or asked permission, just sat down.

Then she began.

Wriggling. Grinding. Gyrating. Not enough so others noticed, but enough to make my cock react.

I could feel it swelling. So could she; she pushed down harder and ground against my lap.

It was too much. I could feel my cock start to pulse as I came.

She knew it.

Then she got up, smiled over her shoulder at me, winked and left.