You can't kid a kidder

I am often repeating the phrase you can't kid a kidder. I am not stupid and I know when some one is not strictly telling me the truth. I can baffle with bulls*** as good as the next man. One of my fellow co. workers ("Idiots?") has now made me use this phrase again as I am typing this. The phone has just rung and of course it was some one he should have rung back hours ago. I apologised and put her through to his office. Out he bobbed after and said "I was just ringing her honestly" "NO you weren't" said I. "yes I was he argued" "NO you weren't because if you were the phone wouldn't have rung in your office" "well I heard the phone ring and put the receiver down my end just in case it was for me". I know and he knows this is so not true the phone rings for ages and ages and he doesn't answer it even when it's right next to him let alone in another part of the building!