Christina Aguilera: Houston's Lunch with Karate Boy Max!

Christina Aguilera holds onto her son Max‘s hand while heading into Houston’s restaurant for lunch on Saturday afternoon (December 8) in Santa Monica, Calif.

The 31-year-old singer was also joined by her boyfriend Matthew Rutler.

Earlier this week, Christina made an appearance on The Ellen DeGeneres Show and performed her song “Just a Fool” with Blake Shelton!

“Thank you @BlakeShelton for performing #JustAFool with me on @TheEllenShow. Had a great time!” Christina tweeted. “Always a riot when I’m with @BlakeShelton. Fun backstage at @TheEllenShow.”

Later that evening, Christina and Matt sipped on Russian Standard Vodka Moscow Mules at a holiday party thrown by producer Jennifer Klein at her private residence.

15+ pictures inside of Christina Aguilera out for lunch…