From Longman Dictionary of Contemporary Englishgagaga‧ga /ˈɡɑːɡɑː/ adjective [not before noun] informal 1 CONFUSEDOLD/NOT YOUNGan insulting word used to describe someone who is confused because they are old Sid keeps forgetting my name. I think he’s going a bit gaga.2 LOVEhaving a strong but often temporary feeling of love for someone SYN infatuatedgaga about/over I can’t imagine why Susan is so gaga about him.
Examples from the Corpus
gaga• Staying home with the kids is making me a little gaga.gaga about/over• Publishers went gaga over celebrity books, with mixed results.• Scores of movie producers, co-stars and fans go gaga over the pretty-baby pout of Sridevi.Origin gaga (1900-2000) French gaga “stupid person” 