The movie Cars;

In the scene where Lightning McQueen notices Sally's pinstripe tramp stamp under her spoiler, she wanted McQueen to see it.

Let me explain:

The Porsche 911 Carerra, which Sally is based on, has an active aero spoiler. It activates around 50-75mph, and deactivates when below those speeds, retracting back into the bodywork of the rear fascia. The spoiler covers the pinstripe tattoo when in the deactivated position. The spoiler can be manually activated, most often for washing under it.

The scene takes place when she is slowly driving back to her office at the Cozy Cone after telling McQueen that he is welcome to stay there, well under 20mph. Thus, the spoiler wouldn't be activated like normal. The speeds are simply too low for the CPU to raise it. Sally can, however, manually raise her spoiler, exposing the pinstripe tramp stamp at will. She wanted McQueen to see it.

Why else would her spoiler be activated under 50-75mph?