A blonde and a brunette are out driving

A blonde and a brunette are out driving, and the brunette tells the blonde to look out for cops especially cops with their lights on.

After they’ve been driving for a while, the brunette asks the blonde if she’s seen any cops.

“Yes,” says the blonde.

“Are their lights on?”

The blonde has to think for a moment, then says, “Yes. No. Yes. No. Yes. No.”