Jessica Simpson Stumbles Out of Hubby's Birthday Dinner

Jessica Simpson let loose at her hubby's birthday dinner, and needed some help keeping it together on the way out of the event.

Jessica was leaving Craig's Tuesday night in WeHo arm in arm with Eric Johnson, who turned 38 a few days ago. We're told the pair was inside the joint for a whopping 5 hours ... which is written all over Jessica's face.

The singer damn near ate it when she almost fell off the sidewalk. Luckily, her hubby and a pap were there to avert disaster. We asked Jess what's her secret to a perfect butt pic ... 'cause she would know.