Hey, happens all the time. I'm still trying to convince my wife that an escaped talking monkey broke into our bedroom, asked me to kiss it, and then turned into a beautiful, 20 year old girl. Sheesh, some people are so cynical!
Hmmmmm! I am trying to think of excuses.
You could tell her that you were spanking the monkey, No, that won't work.
How about, Hi Dear, I was just feeding the monkey, No.
When all else fails, RUN!!! : )