What is a "jumping trojan"? And what do their orbits look like?
In short, most of the trojans stay orbiting arround L4 or L5. These can be called tad-pole orbit asteroids. 

There are some trojan asteroids, however, that their orbit never get's too close to L4 nor L5 to get trapped and have a tad-pole orbit, or they do but they have too much energy to get trapped.

These trojan asteroids have larger orbits, following a path like:

L4 --> L3 --> L5 --> L3 --> L4 and so on. This kind of orbit is called horseshoe.

There is, however, a third kind of trojan asteroid. This one appears to follow a tad-pole orbit (I.E. arround L4), but numerical analysis proves they will eventually adopt a horseshoe-like orbit. When they reach the other stable point (L5) they  will get trapped again in a tad-pole orbit. This kind of orbit is very rare (rarity decreases as planet mass increases) and could be considered (personal opinion) as an hybrid tadpole - horseshoe orbit.

For more information, see:

"Jumping mechanisms of Trojan asteroids in the planar
restricted three- and four-body problems" from: Kenta Oshima and Tomohiro Yanao.