I tried very hard to make my extra credit fun.  Here are a few that I used

EXTRA CREDIT QUESTIONS

I tried to frame my extra credit question to allow my students, or at least a few of them, to answer the question correctly. I also tried to construct them so that they appeared more difficult than they actually were. I always reminded them that the questions were easier than they appeared.

1.  What is the longest English word that contains only one vowel? Answer : strengths. I usually placed the word on the test directly below a discussion question that went something like this. Discuss the strengths and weaknesses of the North and the South in the Civil War.
2.  What teacher at Seneca has coached the following sports; Girls track and field, girls cross country, football, girls basketball, boys and girls tennis, and quick recall (A buzzer Board, intra-school competition where student answer toss-up and bonus questions on educational subject matters ? The answer was Charlie McAdams. (me) the reason it seemed more difficult was that I did not include the sport I was coaching at the time, golf. Some of my kids contended it was unfair not to list golf. My reply, “there is no such thing as fair in extra credit.”
3.  What two verbs in the English language have the most definitions according to the Oxford Unabridged Dictionary? Answer: run and set, both have more than 120 definitions.
4.  What famous television personality graduated from Seneca in 1963? An: Diane Sawyer. Many got this one right.
When did the first Principal of Seneca die? This seems very esoteric and hard to answer but the answer was, he hadn't died. He since has died after living well into his 90's. Kenneth Farmer was his name
5.  What famous cartoonist came to Seneca and gave special permission to use the mascot, Lonesome Polecat? Al Capp who wrote the then very popular Lil' Abner strip. Lonesome was a small bootlegging Indian in the strip. The Mascot has since been changed to Red Hawks from Redskins because Redskins is conceived as a derogatory term. I agree.
6.  What was the first totally integrated high school in Louisville? An: Seneca High School. Seneca was opened in 1957 and one of the reasons was the Brown v. The Board of
Education of Topeka, Kansas. In the ruling the US Supreme Court found that the Plessy v. Ferguson ruling in 1896 which allowed governments and businesses to keep races separate with the caveat that facilities must be of equal quality, was Unconstitutional and that public facilities must desegregate. With that in mind, Jefferson County School set up Seneca as an integrated school in hope that that would suffice. It didn't and forced busing was instituted in 1975 (?)
7.What is Louis Armstrong's actual first name? Answer, Louis. Trick question.

Speaking of extra credit, I began my career with making the extra credit question 5 or 10 points extra and I noticed that my pupils would cheat on this question more than on the actual test itself and I was giving out a lot of extra credit. I finally thought of a way to stop it. I starting making each ec question worth one point for every member of the class. If I had 30 in the class, the question was worth 30 point total, not per student. That way, if only one person gave the correct response that that person go 30 points but if two people got the correct answer, they each received 15, if three did that each got 10. You would not believe how protective the students became over those few points. It was one of my best moves and I was able to tell the student that it was perfectly okay to share the ec answer. They didn't.