EXCLUSIVE

The Chattanooga Lookouts are a minor league baseball team affiliated with the L.A. Dodgers ... they're also the only team with a picture of a naked man's tattooed ass hanging in left field.

This photo was taken yesterday at AT&T Field in Tennessee ... showing what appears at first glance to be a harmless ad for Champy's Chicken right near the scoreboard.

Upon closer inspection ... turns out the Champy's logo is actually a tattoo that happens to be located on the right ass cheek of a very big Champy's fan.

A rep for the restaurant tells TMZ ... Champy's gave the ass model $200 in store credit so they could use the shot in their ads. The credit was all up front ... so, the model gets nothing in the back end (rimshot).