BD-5 - the smallest jet aircraft in the world created in the 1960s by Jim Bede - US aircraft designer. The BD-5 has a small fuselage, small engine installed in a compartment, and small propeller (or jet engine in the BD-5J variant) in the rear.
BD-5J Looks awesome, it very small and convenient, it can be carried with yourself to the outdoors and when you will feel bored, start flying =)
Some general characteristics of smallest jet aircraft: weighs 162 kg, is 3.7 m long, has a wingspan from 4.26 m to 6.55 m (depends of used modification), and can fly at 483 km/h (300 mph).
see also Largest airplane in world
Some video: