It shows that you are clever, smart fun and down to earth in ways that a direct claim will not work. It also makes you seem more approachable. Don't use humor at others expense. Don't use off color humor. Don't use too much self deprecating humor. This can be misinterpreted as a lack of self confidence. Don't worry about making everyone laugh because you will always confuse and even turn off some. The people that get a Kick out of your specific brand of humor will most likely be fun to be around.