One of the common tactics of believers in Young Earth Creationism, and devotees of Answers in Genesis, is to reply to statements about evolution with the question, “Were you there?” Ken Ham has been pushing this approach since at least 1989, and it’s dishonest horseshit, as I’ve explained at length.
It really is a stupid question, but now my eyes have been opened, as Roger Patterson of AiG explains exactly what the question is intended to do.