Any temporary, unlighted signs, not exceeding two square feet in a residential district, advertising the sale or offering of pets, personal or household articles or a vehicle, trailer or boat belonging to the owner or occupant of the premises, or signs pertaining to campaigns for local, state or federal office, which shall be removed promptly following the sale or disposal of the pets or the articles or after the election has taken place. This exemption permits no more than two such signs per premises.