The phrase "dead frog" refers to a frog that has died. It is often used metaphorically to describe something that is lifeless, uninteresting, or lacks energy.
Sentences with «dead frog»
People who see large numbers of dead frogs, or frogs with strange diseases, are asked to contact the FMP (Tel: 098-684 518). (newscientist.com)
Adapted from the chapter «Beating Dead Frogs with CO2» in Landscapes & Cycles: An Environmentalist's Journey to Climate Skepticism by Jim Steele (landscapesandcycles.net)