Ashley Benson (Hanna) and Selena Gomez became besties when they co-starred in Spring Breakers together, and it looks like this pretty little friendship has only gotten stronger.

Ashley took to Instagram over the weekend, posting a photo of SelGo smiling with her birthday candles. Along with the pic, Ashley wrote, "Happy 21st baby!!!! @selenagomez."

While we're not sure where these ladies celebrated — it looks like a private room at a restaurant, or at someone's house — we do know one thing: Selena's cake was not so sweet. "My cake was... Jack n the box tacos... Yes," she wrote on Instagram. Now that's our kind of dessert!

What do you think of Selena and Ashley being BFFs? Let us know in the comments below!

Credit: Ashley Benson's Instagram Photo: Selena Gomez's Birthday Cake