Including a joke in an otherwise correct exam answer as the student
As I understand, your main question is:
Could it impact the immediate and/or long term evolution of my grades, education and professional/academic life beyond just this exam, whether negatively or positively?
Immediate grade: Obviously. People might have different rules on how they grade. Graders are usually humans who are impacted conciously and subconsiously by their students' actions (and how they speak, look etc.) One teacher might like you more for making jokes, one might be angry that you wasted their time, one might not find the correct answer because you wrote too much irrelevant things etc. One might not care. In grading, almost everything is possible.
Long term evolution of grades, life: Most likely not. If you have one teacher in different courses who likes you or doesn't like you because of jokes, this might play into other exams. However, usually, after a course is over, if at all, people care about the grade you got and not why you got it. It's unlikely that anyone will see the exam after the end of the course.
If you get extremly famous, it might be a nice episode about you that you made jokes on exams. Or not.