Rat? Or a middle-aged man?

My colleague gave me this hand-written card along with some sweets for the new year. I tossed the card on my desk and there it remained for a couple of days, turned sideways.

I glanced at it one day and made a startling discovery:

Hand-drawn illustrration of Year of the Rat greeting
Mouse, or ojisan?

This was definitely unintentional, as when I pointed it out to her it took her more than a minute to realize what I was talking about. And then she said, “A western ojisan, possibly! Not a Japanese one.”