Know I'm playing or think I'm psycho?

From what you have said, it sounds like they know you are playing with them, because they get excited. With my rabbits I like playing tug of war with some hay. I know they like it, because they have piles of hay available to eat, but they will choose to tug on the piece I am tempting them with.

Not many people answered because no one probably does that with their guinea pigs, haha.

I do the same with my pigs! My one piggy Basil (well ok, he is my mums piggie) loves that game! I dangle it in front of his face then pull it away a bit then he popcorns and go chasing after it! Its sooooo cute! I think the piggys know its playing and not trying to hurt them or else they would run off!