Haha! He misspelled Rikku! Now let's all laugh at him and pretend to not know what he's talking about even though we're more than capable of doing so! You silly billies. ;P
I don't think Tidus and Rikku have a thing at all. I didn't sense any chemistry there. WISHFUL THINKING
Actually, they were doing that because he is too lazy to type correctly. I am pretty sure he is intelligent enough to spell the character's names right. They were pretty much making fun of him for that reason, which is perfectly justified.