Simple as it looks, stand-up would be something that your dwarves do when they have "No Job", which will increase their "Comedian" skill, give them a good thought (If they did it right) and will also give a good thought to those who are watching (If he did it right). Dwarfs won't get a bad thought if the stand-up failed, but the comedian will.
First, a "Entertainment zone" should be created, so the comedian will perform there. The zone would also need to be inside a meeting hall, otherwise, he would just stay there, telling stupid dorfs jokes all alone. After the zone is done, the comedian will sometimes go on that area to perform the stand-up (When "No job"). His linguistic ability would also affect his perfomance.
Also, bards. They would work somewhat like the comedians. They would perform in the same zone that the comedians perform. Unlike the comedians, the bards would need to train their skills to perform. They would do this in their room, or, if they don't have any, anywhere they feel like. There would be a skill to determine their ability with instrument, such as "drum player, flute player, harp player". Their performance would also be affectedby their musicality. If their perfomance was good, they and the dwarves who were listening to him will get a good thought. If he failed, he will get a bad thought.
Both of these would be jobs that the dwarves would perform if they have no job to do.