Stranglehold

In the Slums of Kowloon level, stay along the top pathway in the crumbling sewer area.

Complete the Tai O level on any Difficulty setting.

Host and complete 10 multiplayer matches on the Kowloon Teahouse map.

Fire 10,000 times.

Complete The Mega Restaurant level on any Difficulty setting.

On any difficulty setting, complete a Standoff by defeating all enemies without taking any damage.

Kill 50 opponents using Tequila Bombs in Multiplayer matches.

Complete the Wong's Estate level on any Difficulty setting.

Complete the Zakarov's Penthouse level on any Difficulty setting.

On the first level you can get it pretty easily by stringing together all you kills in the second area you go into. Slide down the long banister and shoot the signs off to kill everyone below, then dive onto the roll cart at the bottom and roll across the market square and towards the other set of stairs leading back up.

Kill the 3 guys that come out of the door to the left of the stairs to spawn the ones who comes out from on the stairs, then just run up the banister (or just run up the stairs like normal) shooting all the signs and vents above them until you get to the top.

It might take a few goes to string it all together but if you do it right you can get a combo of over 50+ style points no problem (my top record on that area so far is 79).