A Blip of a B... or is that C...

Suz and I rarely argue, but I got the guitar out on holiday and was playing around with some chords I've been working on. She started humming along and it sounded great, until she asked me what notes and chords I was playing.
My answer was that I didn't know, and then we started working them out, but she got angry and confused about the job of a capo.
In my opinion, a capo helps me play notes that I otherwise wouldn't be able to... and I don't care what it actually does! Suz on the other hand needs to know what it's actually doing...