At Nairobi, I saw on a taxiway in front of us a frog doing a slow gentle hop across the taxiway in our taxi lights. As he had the eminent good sense to do it at 90 degrees across the taxiway, I brought a 747 to a halt and waited for him to hope out of the way. I made a short PA to the passengers to advise them there was no problem, just 'waiting for a frog to clear out of our way', then we continued. There were no complaints.