A crackling sound is heard while taking off sweater during winters. Explain the reason behind this.

As we know that electrical charges that are generated through friction are static, i.e., they do not move by themselves and Motion of charges constitutes an electric current. When we take off our sweater there is a motion between the charges on the sweater and our body that produces electric current, which produces a crackling sound. We can see a spark if we take off the sweater in the dark.