Prey

This Achievement will be unlocked after you made 25 kills using the Acid Sprayer, both functions work. This is the sixth weapon from your equipment.
Tips:

• Find someone to trade Achievements with
• Create a Player Match:

Map - Roadhouse
Game Type - Team DeathMatch
Frag limit - 25
Time limit - Infinity
Max. Players - 2

• Meet with your buddy at a place which is easy to find, like the basement.
• Kill your buddy 25 times with the weapon of your choice.