Not sure if this has been posted already, if so, my apologies.

But, If you want an easy way of killing the doctor before he steals your weapon and not doing the table glitch.

Stay int he first room, purchase the M14, and the Revive Cola. Stay int hat room, getting as much points as possible. Then once you reach Round 4, make the last guy a crawler, then go downstairs and turn the power on and go back upstairs. Kill the crawler and head for the elevator(the one that leads to the power) Wait in the elevator, if the doctor doesn't appear, buy the Stakeout, or MP5 and survive till around round 7 or so, that is when he came for me.

Now once you get the doctor. Go to the elevator and as the room fills with smoke and the announcer says "Breach Detected) face the teleporter in the room and cook a grenade, put yourself down and spam the Pack a Punch pistols at the doctor, you should kill him and be rewarded the achievement, ammo, and pack a punch bonus that lets you upgrade your guns for 1000 points.

This is a do with only 1 person thing.

Again sorry if it has been posted.