I realize alot of teams go Frost Mage and Rogue for 2v2 (I myself prefer a resto shaman), but today I found a trick with sap. If you sap the enemy and let your friend cast something at him and then resap right after he throws it, then your target stays sapped for another free cast. Timing has to be decent and your friend can even throw an instant right after the first cast and you can still resap (As long as its not a DoT) If you can time the sap right.