Answer:
This happens due to static friction
Step-by-step explanation:
Static electricity is an imbalance of electric charges within or on the surface of a material.
The friction created when your clothes rub together causes an electrostatic charge to build up on your clothes due to the triboelectric effect. This charge is transfered from one piece of clothing to another making some clothes become positively charged and others negatively charged. This causes the clothes to stick together.