No More Monkey's Jumping on the Bed

My three children have always loved our king sized bed.
And they would jump and play on it for hours.
And still, even now, they love to come over and lay all over my king sized bed.
Apparently, it's being passed down to the next generation as Preston too, loves to jump on Grandma and Grandpa's bed....It seems to be the second favorite gathering place for our family, the first being the kitchen table. (kitchen area).
So it's all I can do to keep these monkey's from jumping on my bed.