To be wild about (something)

Idiom: To be wild about
  

Meaning: To have a strong, almost uncontrollable, liking to someone or something. 

Context #1 – Someone has fallen in love.

Matt: Leslie, I have something to confess. 
Leslie: Okay, what is it?
Matt: Well, we’ve been spending a lot of time together these days, and well, what I’m trying to say is I’m kind of wild about you.
Leslie: Oh Matt, I feel exactly the same way.  I can’t stop thinking about you all the time.
Matt:  Really?  I’m so happy to hear that because I feel that way too.  I really like you and just want to spend all my time with you.


Context #2 – Talking about baseball between friends.

Don: I love baseball season.  There’s nothing better than a good ballgame.
Summer: I know.  Every year you say the same thing.  Why are you so wild about baseball?
Don: Everyone I know likes baseball.  I’ve been watching and playing baseball since I can remember.  The games, the players, the food, the atmosphere can make your entire day fantastic.  I’m more than wild about it, baseball is life.
Summer: I guess I can’t argue with that.  Besides, baseball has become popular in many countries now. 

Meaning: The idiom “wild about” means to like something very much.  Being wild about something means you can like something to an extreme, for a brief or extended time.