Grandfather’ birthday is a great reason to bring him positive emotions on this day. For example, he will be glad to hear all the pleasant wishes that will be addressed to him. Also, he will be happy to receive a gift, if you have an opportunity to give it. Present him greeting e-cards with nice images. These pictures are funny and there are even pictures with memes. The effect of such congratulation will be great, but that's what you want to achieve.