This entry has now been unfriendslocked - I have realised the error of my ways.

And basically, the joke is this: Misa is having Spanish lessons and Light is very jealous, because he thinks he *should* be the one learning it. Misa asks his dad what he thinks of this decision and he says this -
"Now now, let's not make Light of the sí tuition."

...Yeah, I was bored yesterday. xD