Can a body both topple and slide? When a body topples about a point, I'm clear about the net torque acting on the body, just wondering if the toppling can happen if there is no friction or not enough friction; can there be a situation when the point of contact of the body with the ground slides and the body still topples ?
 A: Yes you can tip an object that is sitting on a frictionless surface. Let me show you how.
Consider first the case where the object is in a vacuum in free space. To create rotation I need to apply a torque to the object. Consider now that if I push the object anywhere other than  the center of mass. For example, visualize a bar where I am pushing sideways at one end. The object will begin to rotate about the center of mass since the side with more mass resists my push more than the one with less. 
Now back to your question. If you push an object at the center of mass while it is on a frictionless surface it will only slide and will not topple. However, if you push it away from the COM then as above there is a torque and the object can topple.
Note that these are not exclusive though, the object could start sliding and then topple or could start to slant over but then just slide upon finding a new balance point. It all depends on the specifics of the problem beyond the simple thought experiment above.
