We would inflate inner tubes and slide down grassy hills. Also, dragging things behind a car (like a car hood, or a cahir (That is "chair" in poor typist-ese) from Salvation Army that has rollers), and trying to ride it.
"Throw the ball real hard at the other person's face and see if they can stop it" is another great one. Easy to explain, too. We would ride my sister's hog (a big fat pig) around, trying for eight seconds. Yeah.