The triboelectic charging process (a.k.a., charging by friction) results in a transfer of electrons between the two objects that are rubbed together. Rubber has a much greater attraction for electrons than animal fur.
The electrons get rubbed off some items onto others. This causes an excess or electron on one item and deficiency of electron on the other. Therefore an electrostatic force of attraction is produced and hence clothes often cling together after tumbling in a clothes dryer