baby announcement

I have told almost all my family that I am having a baby but I haven't told my father. I rarely see him but we are very close. I want to announce it to him in a very special way. I'd like to surprise him with a cute announcement that he's going to be a grandparent. It won't be his first because my brother has a 7 yr old boy. I was thinking of engraving a beer glass as "Grandpas Beer" but I think there could be other creative ways of telling him. I'm not sure how he'll react since I'm his first born...  so I'm trying to lighten the situation. Any suggestions?