First Put a Claymore On you and your teammate
Then what your going too do is shoot the claymore and you and your team mate get infected (You Get Points also)
Ta-Da!!! Good For Trolling around with your team mates!!!
UPDATE:STILL WORKS GUYS JUST TRIED IT 3-19-2012!!
Do it with a c4 and OMG QUAAAAAAAAAAAAAAAAADDDDDDDDDD!