Appears to be killing without using a weapon. 

http://battlelog.battlefield.com/bf4/battlereport/show/1/895998373480923968/358379695/

Odd one.  82 kills, 58 headshots.  But...  with what weapons?  Best weapon has 8 kills.  Best vehicle has 26.  He has 5 MBT ribbons so that's 25-29 kills in a tank so there's no other MBT kills hiding other than those 26.  One sniper rifle ribbon. 

And same basic thing here: http://battlelog.battlefield.com/bf4/battlereport/show/1/895628613555015104/358379695/

61 kills, 39 HS, but most used weapon was SRAW with 2 kills, best vehicle was LittleBird with 27 kills.