are there any multi engine aerobatic aircraft?

Yes. The CriCri is one.

Any aircraft can be aerobatic to an extent if you don't exceed the g-limits or the allowed time for inverted flight. When the Boeing 707 came out in the 1950s, the pilot performed a barrel roll a few hundred feet above ground. But by true definition, there are very few if any multi-engine aerobatic aircraft.

http://www.youtube.com/watch?v=-KNbKFMBsQE&feature...

I can not think of any multi-engine plane certified in the aerobatic category.

Almost any aircraft is capable of basic aerobatic maneuvers, but that does not make them an aerobatic aircraft. Bob Hover did amazing airshows in his Aero Commander Shrike, but had it registered in the experimental category for use in airshows If you happen to own a Shrike, you can not legally take it out for some weekend loops and rolls.

Many fighter jets have two engines (f18, f22, eurofighter) just to name a few and they are deff aerobatic airplanes. >.>

Oh, there are a few.

Shrike Commander & SabreLiner (Mr. Bob Hoover)

http://www.youtube.com/watch?v=gZPyM2PJcFM