Paintballing
My friends gave me this as a present so I took my girlfriend along - I wasn't sure if she'd like it as she had never been into this kind of thing, but as soon as she had taken her first shot, there was no turning back!
I really enjoyed the paintballing - I knew it would be competitive, but I had no idea that we would all get into the spirit of it so quickly. I'd definitely go again and since I came back, all my mates want to come too.