favorite number

For the last while Joseph's favorite number has been 48. I'm not sure why this is, but it is. And he has stuck with it. He wanted his bedtime changed from 8 to 7:48. (oooooookay?) He set various alarms on my phone. (11:48 pm, 12:48 am, 1:48 am . .. ugh). Every time he saw a 48 he got excited and exclaimed, "it's 8:48! or 9:48!" (you get the picture.) He was equally disappointed if he missed the 8:48 or 9:48 or . . . . etc.

He just got home from school a few minutes ago and announced:

J1: "mama, I changed my favorite number."
me: "it's not 48 anymore."
J1: "no. now it's 58."
me: "it's 58 now, not 48?"
J1: "yes. And do you want to know when I changed it?"
me: "sure."
J1: "on January, Friday the 21nth." (as in twenty oneth.)