Why is Mischa Barton so pissed off in this picture? We have some theories:

• She hates pumping gas even more than Nicole Richie does.

• She can't shake the image of Cisco Adler nude from her head. Yikes.

• The curtain she's wearing as a dress could be uglier than a similar outfit donned by Kate Bosworth a few months ago.

• She just realized that Autumn Reeser is a much better actress on The OC than Barton ever was.

We can't say for sure. And we do admire Mischa for pumping her own gas. It's something we can't exactly see anyone on MTV's The Hills doing.