wild about, be - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Be highly excited or enthusiastic about, as in She was just wild about that jazz band. This usage replaced the slightly earlier wild after. [Second half of 1800s]