I Happen To Be An Expert (On This Subject/Topic)
From the nearest I can tell, the original seems to be this macro from Bill Nye the Science Guy
It dates back to at least 2008 (seen in Post #14 here)
Was this phrase ever said by Bill Nye in the show? Is Bill Nye actually the original image used, or is it just one of the variants, with the original being something else? The image used in the Photography-on-the-net forum was embedded from a blogspot, but I can’t find any blog older that uses it. I found older images of Bill Nye like this (2006) using reverse image search, but they lack any connection to “I happen to be an expert.” I can’t seem to find anything older for the text version at the moment.