Louis recently told Top of the Pops magazine (via Unreality TV): "I think maybe Liam [is my victim most often]," adding, "I don't know why. He's not gullible or anything. I just think it's cos me and him banter with each other a lot and he gets the brunt of it. Every now and then during a concert I'll change a few song words to something random and stupid, just to throw the boys off."
And speaking of in-concert pranks, a fan captured Louis at a recent show in Tokyo, pouring water into Liam's hood. Watch his reaction!