A statement, statements or a series of statements made by an individual (usually the same individual) that are so obvious the person hearing these statements can simply stare at the stater expecting to him or her to laugh indicating they are joking. However the laugh never comes because the person believes the question to be legitimate.
Scott - Have you heard the latest Tommyism?
Josh - No. What did he say now?
Scott - He just looked at me and asked, "Scott, how many teaspoons are in 3 teaspoons?" I thought he was joking... He wasn't!
TV Narrator - There are as many stars in the universe as there are grains of sand on Earth.