I experienced the opposite phenomenon this evening: I heard a human, in the real world, speak Simlish!
I was at the grocery store and, as I was pushing my cart up the aisle, I met a young woman heading the other way. Her phone rang, and she stopped to take the call. Then, she greeted the person on the other end with "Sul sul!" My daughter was with me, and she couldn't help giggling at her.
"I think she plays The Sims," Daughter declared to me...loud enough for the woman on the phone to hear.
She simply smiled and nodded "yes."