David Oyelowo says Charlize Theron's not shy about using colorful language, and if ya don't believe him ... check out this video. She proves his point, and then some.
The actors -- who costarred in the movie "Gringo" -- were participating in a Q&A this week at a Bev Hills charity gala for The GEANCO Foundation. When Oyelowo was asked about his first encounter with Theron, the crowd got a jaw-dropping tale ... about anuses.
He warned the audience it probably wasn't appropriate -- especially with his family in attendance -- but Charlize had no qualms ... and dropped a crack about bleaching your crack.
It's hard to tell if her account of the anal bleaching conversation -- or lesson, as she puts it -- is 100 percent true or if she's just busting David's balls, but the audience ate it up.
The laughs continued when the host asked David a very fitting follow-up question, then David's young daughter topped it off by asking for some more clarification ... from dad.
Anal, sorry ... ALL humor aside, the event also raised money for a very good cause. The organization helps African women and children in need.