Linguistics in the wild

Mixed Metaphor overheard yesterday:
Undergrad looking Girl to Undergrad looking Boy: "It's going to be awesome! I think you guys are going to be head over heels in girls."

I was kind of surprised at how good it sounded for a mixed metaphor. I think Lakoff calls these "impermissible" mixed metaphors. I think Lakoff was wrong. Because it didn't seem to interrupt their conversation at all and it took me a few seconds to figure out what was wrong with it...