Kill 5 predators in less than 5 seconds can be done on the UP AND OUT single player level. I think it's much easier than trying the auto-aim & quick shoot trick in Maneater levels.

When you get to the arena section with the baboons, kill the first 2 waves. Then have your shotgun out (for the spread as baboons are easily taken down with 1 shot) and get to the LEFT side of the arena. Wait til they all in front of you. They tend to bunch together. It should only take you 3 or 4 shots as you will certainly get 2 for 1 with the shotgun as well. If done correctly, then you will kill all 5 of that 3rd wave within 5 seconds.

Here are the waves:
- 3 baboons that attack
- 4 baboons that attack
- 5 baboons that attack