So I am on the mission with trevor called Predator, basically you chase the O'Neil Brothers, they crash and run into the woods, well when you are in thermal vision with the sniper, I shot the one guy in the water, and the other guy to the right of him, and when I went for the third guy (with a rocket) I saw bigfoot, it was only there for a couple of seconds, but it was really detailed and you could actually tell it was bigfoot, I guess its just an easteregg or something, I didn't get a picture or anything, I wasn't prepared for it aha, but incase you have done the mission, or you want to go replay it, you may be able to see bigfoot..