My 4# Romeo loves to run really fast past my 1.6# Denero and swat and him with his paw and either flip him on his back or completley flip him over once...I feel bad for Denero but it is pretty funny...he sits up and looks around like "huh, what happened??"....He's growing so he is starting to chase after him...won't be long and he'll be kicking Romeo's butt!