A Texan farmer goes to Australia for a vacation.  There he meets an Aussie farmer and gets talking. 
The Aussie shows off his big wheat field and the Texan says, "Oh!  We have wheat fields that are at least twice as large".

Then they walk around the ranch a little, and the Aussie shows off his herd of cattle.  The Texan immediately says, " We have longhorns that are at least twice as large as your cows".

The conversation has, meanwhile, almost died when the Texan sees a group of kangaroos hopping through the field.  He asks, "And what are those"?

The Aussie replies with an incredulous look, "Don't you have any grasshoppers in Texas"?