F-82 Twin Mustang

From a post by mrsekt on Military Photos dot net:

It looks like something a kid would dream up, but they really built them. They were too late to participate in WW2, but they proved to be quite effective in the Korean War.

From Wikipedia:

"On 27 February 1947, P-82B 44-65168, named Betty Jo and flown by Colonel Robert E. Thacker, made history when it flew nonstop from Hawaii to New York without refueling, a distance of 5,051 mi (8,129 km) in 14 hr 32 min. It averaged 347.5 miles per hour (559.2 km/h).
[...]
To this day, it remains the longest nonstop flight ever made by a propeller-driven fighter, and the fastest such a distance has ever been covered in a piston-engined aircraft"

P.S. Note that the record is for "a propeller-driven fighter", not a propeller-driven airplane.