A blond and her blond boyfriend went for a walk along the river.
The blond walked across the river alone on a wooden bridge. After crossing the river, the bridge collapsed.
She called across to her blond boyfriend telling him that she couldn't get back.
He yelled back, "Wait until dark, and I will shine my flashlight across the river. Get on the light beam and walk back."
She replied, "No, I'll get half way across the river, and you'll turn the light off!"