Most people know this one, but most people don't know it's part of a larger painting called the Sistine Madonna. The angels look intensely bored, but they're looking at Mary holding the baby Jesus. I guess that by the time of the New Testament they were used to all the big brouhaha about burning bushes and pillars of fire, so here they're like "yeh u gotz babeh kthxbai".
Or maybe they were just thinking about other things. Like getting some wimminz.