From an esurance commercial on tv, entitled “Hank” (the key bit is boldfaced):
Hank: My daughter thinks I’m out of touch. So I asked her how I saved 15 percent on car insurance in just 15 minutes.
Neighbor: Huh. (shakes head)
Hank: (looks at phone) “IDK?” What does that mean?
Neighbor: “I don’t know.”
Hank: And I’m the one who’s out of touch. LOL.
The neighbor is answering Hank’s question, a request for information, asking about what “IDK” means. Hank understands this instead as an assertion, by the neighbor, that he doesn’t know what “IDK” means. (Hank then thinks the neighbor is out of touch.) Both understandings involve assertions, but about different aspects of the conversational exchange.