We won't hold it against her, but we're pretty sure Britney Spears just spilled a big secret -- she accidentally called boyfriend Jason Trawick her husband!

The slip-up came while the "I Wanna Go" singer was visiting the U.K.'s KISS FM radio station last week. The DJs were chatting with Brit about her son Jayden's 5th Spiderman/Batman-themed birthday party, and they wanted to know if Ms. Spears dressed up for the occasion -- or in general! "Actually me and -- I was going to say my husband -- my boyfriend, we do that every once in a while ... We're goobs. I'm so embarrassed!" Brit exclaimed.

This comes just three weeks after Jason was spotted looking at diamonds with a Beverly Hills jeweler.

They may not be married yet, but both seem excited to take that next step ... soon!