Isn't it funny

[Bob's Orange]

How when you kick one of those cheap 'flyaway' balls, it swerves the opposite way you may expect!!

[STFC Village]

SUPER TELE!

[genf_stfc]

reverse magnus-robbins effect. kicking a ball with spin will make it act like an aerofoil and cause lift in the direction of the spin as the air has to flow faster round one side of the ball than the other.  but if you really belt something like one of them petrol station balls, the side thats spinning in the direction of travel has an increased relative speed to the passing air and causes turbulence at the surface of the ball on that side - this causes drag which causes the ball to swerve in the opposite direction.  

I seem to remember this happened when the rotational velocity was less than 40% of the forward velocity, but i'll let someone else wikipedia that while i get my coat (white coat with all pens in the pocket).