Color Blind

For months now I have been stressed about Jake's mastery of his colors.  I know it sounds silly.  He is only two and a half.  But I could not figure out how a child who can accurately locate and name a dorsal fin or tell where his frontal bone is could not identify the color yellow.  I have been doing everything I can think of to surround him with color learning.  We paint, we color...with markers, crayons, colored pencils, even colored chalk, we use color paper to make sicker art.  I made color matching games.  We group just about every toy he owns into color groups.  On walks we discuss the colors of the trees and flowers around our neighborhood, on drives we talk about the colors of the other cars that pass by.  While he has always grouped and matched like colors correctly, naming them correctly is pretty hit or miss.  I was beginning to think it was hopeless.  My father is red-green color blind, so I have understanding when it come to anything made up of those two colors.  However, two nights ago when I asked him about something yellow and he told me it was blue, I turned to Arthur and said, "I don't know what to do.  He really can't learn his colors."
Arthur, who is now a very busy flight school student, barely looked up from studying, "He knows his colors."  The calm and confidence in his voice upset me.  Does he not understand?!?  We have been working on this for months...I am at a loss.  I immediately had visions of Jake as a grown man, forever stunted in his life progression, because I had failed at teaching colors.  But before I broke down in some hormonally induced scene, Arthur explained, "He thinks it's funny to tell you the wrong answer."
Of course I argued with this.  "No, I really don't think he knows!  He just told me yellow was blue!"  Obviously, my husband was not seeing the severity in this.  Blue and yellow are practically opposites on the color wheel.  Not to mention, they are primary colors!! I quickly dismissed his ridiculous theory, who would purposely and continually give the wrong answer? 
Later that evening we headed to the park.  Jake and Arthur were busy running around when Jake announced, "I want to go to the purple slide."  I didn't give a second thought to his question until Arthur said, "Did you hear what he just said?  Doesn't know his colors, huh?"
Back at home I was moping the floor while Jake played in the family room.  Apparently, I had missed some of the dinner's runaway jello because Jake pointed to the corner and said, "I see something green over there."  Sure enough there was the green jello hiding under the table leg.  I froze and just stared at my son for a moment and let it all sink in "You do know your colors!" I exclaimed.   Without saying anything Jake nonchalantly turned around and continued what he was doing.  How long has this been going on?  How long have I missed this?  I have been too caught up in him answering my questions correctly that I wasn't listening to what he was really saying.
As for who would be wrong on purpose...to be funny?  Certainly not me, but apparently I forgot that two of us made this little person.  Guess that is why Daddy was the one to catch on to this little game first.  Boy, or should I say boys, am I in trouble.