He stops and tells them to get rid of the sign or he will run them in!
They comply and he proceeds down the street only to pass a man with a sign that says "Jesus Saves".
The cop just waves as he passes and the girls see this.
The next day they are waiting on the cop to drive by and as he does they flag him down. The girls say that they saw him let the guy with the sign down the street keep his sign, and they don't think that he was fair with them.
The cop says "You two dummies! That was a religious sign!" and drives off.
The next day he drives by and low and behold the gals have a sign that reads
Spoiler:
