With lol you are greeted every day with the latest nerdy humor from xkcd. .
One thing that I think people really don't understand is that fun ≠ unprofessional. We aren't robots. We're people with feelings and emotions and sometimes we need to laugh.
Sometimes that chuckle determines whether your work day is fun or blah. As I've always said, "a dad joke a day keeps the sadness away".
To add lol to your site check out the documentation here.