The Geico Gekko, even though it is animated by use of CGI, is considered real in Toobworld.
As to why a gekko can speak in this televersion of the "real world", Toobworld Central has never bothered to think of a splainin - as was the case for 'Mr. Ed' (a refugee from the Island of the Houyhnhm as seen in "Gulliver's Travels".) "For alls I know", he could be an alien from another planet....
At any rate, this blipvert will probably rank as the 2012 Toobits winner for "Best Crossover Between Toobworld and the Tooniverse".