A short fact that can be about anything, as long as it is interesting and fun. A fun fact can be told at any time and doesn't have to be relevant to anything. A true fun fact should be memorable and make people laugh. Beware: You should never repeat a fun fact that another friend has told, fun facts are only fun the first time they are heard.
In conversation:
Lauren: "Hey everyone, do you want to hear my fun fact of the day?"
Friends: "Yesss please tell us!"
Lauren: "If you yelled for 8 years, 7 months and 6 days, you would have produced enough sound energy to heat one cup of coffee!"
Friends: "Wow! That was so much fun! You have really brightened up our day!"
A kind of fact that disguises itself as a "fun fact" but it is not fun at all.
Person 145: "Wanna hear a fun fact?"
Person 223: "Sure."
Person 145: "We are labeled as numbers because we are subjects for these made-up conversations."
Person 223: "That is not fun at all..."
Person 145: "But it is a fact."