be nuts about (someone or something)
1. To be very passionate and enthusiastic about something. My daughter is nuts about sports—she's currently playing soccer and tennis and taking swim lessons.
2. To be very romantically interested in or in love with someone. I've seen the way Tim smiles at you—that guy is nuts about you!
be nuts about (or on)
be very enthusiastic about or fond of. informal 1934 Dashiell Hammett The Thin Man She told me she had this job with Wynant and he was nuts about her and she was sitting pretty.