Question

We tend to slip if we accidentally step on a banana skin

Answer 1

As we know friction is necessary for a body to walk because according to Newton 's third law of motion, (every action has an equal and opposite reaction), therefore, we can walk only if the ground we are walking on push our feet back with a force. Friction helps us by providing the necessary reaction force.

If we step on banana and try to move the friction between the fett and banana is not sufficient to push the feet to support walk. So we slip off and fall when we step on a banana.