It varies. There are comics that deal with adult issues and are intended for mature readers. However, there are also plenty of comics that are enjoyable for people of all ages, like those with simple and fun stories.
There were some adult neighbors who had a friendly competition every Christmas to see who could decorate their front yard the best. One neighbor, instead of the traditional Santa and reindeer, made a whole scene of elves doing yoga. There were elves in downward dog and tree pose. It was so unexpected and funny that people from all over the neighborhood came to see it and had a good laugh.
One funny bedtime story for adults could be about a clumsy wizard. He tries to cast a spell to make his shoes shine but ends up turning his whole house into a disco ball. Everything in the house starts to glitter and play disco music, and he has to figure out how to reverse the spell while dancing along to the beat.
There was a couple, Jane and Mark. One night, as they were getting ready for bed, Mark accidentally sprayed hairspray instead of deodorant under his arms. When he realized what he had done, he started waving his arms around trying to get the smell out. Jane saw this and burst into laughter. Mark then joked that he was trying to create his own personal 'scented cloud' for a good night's sleep. They both laughed so much that they forgot about the initial annoyance.