Vinyl Mice.

They were living mice, but instead of fur, they had skin made of vinyl. They were cute little scutters, wish I could have taken a picture.

The males were white, the females were green.

You could take a male and place it on a female and it would mate with it.

You could take a male and place it on another male, and it would attempt to mate with it. Usually a fight broke out.

My wife says the females were green because the green M&M's are green and somehow that got into my subconcious!