Hi there. I have been having this argument with my boyfriend for a while now, over the colour of a tennis ball (I promise we're not as sad as it sounds). I know that tennis balls can come in all colours e.g. orange, cream, white etc, but it's the "normal" tennis balls. Now I think that they are yellow - a very bright yellow, but yellow nonetheless. My boyfriend thinks they're green. I'm calling on the people of tMP to settle this once and for all!