See cute pictures of Sean Penn going grocery shopping with girlfriend Charlize Theron and her 2-year-old son Jackson in L.A. on Jan. 22. Credit: Chiva/

Boyfriend on duty! Sean Penn joined girlfriend Charlize Theron on a trip to the grocery store with her 2-year-old son, Jackson, in L.A. on Wednesday, Jan. 22. The 53-year-old actor helped keep Jackson happy while Theron, 38, picked up items she needed. Click here for more photos of Charlize and Sean.

Penn made funny faces at the tiny tot, while he sat in the shopping cart at Whole Foods. The Milk star also helped Theron by pushing and unloading the cart, and loading bags into their car.

Penn wore a light denim shirt and jeans for the outing, while Theron looked stylish in an open-back black top, skinny jeans and sandals. Little Jackson, whom Theron adopted in March 2012, looked adorable in a black T-shirt, rolled-up jeans and slip-on shoes.

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After a job well done, the South African star gave her new man a pat on the butt before heading into their car.

Theron and Penn were first rumored to be dating when they were spotted ringing in the New Year together in Hawaii. In a Jan. 18 blog post, Piers Morgan confirmed they were a couple by sharing a conversation he had with Penn at the Jan. 11 Help Haiti Home gala.

"At 2 a.m., Sean came over, and bear-hugged me," the Piers Morgan Live host wrote. "'Congrats on a great night,' I said. 'And congrats on Charlize too.' He laughed. 'She's a keeper, that's for sure . . . well, I'll do my best to keep her anyway!'"