The idiom 'Crazy as a loon' is used here to describe someone acting in an abnormal way.. Thankfully I don't hear it much anymore!
Canada has a one dollar gold colored coin that has a loon engraving on it. It is affectionately called a Loonie.
And yes. LoonieTunes. I've heard that used to describe people, as in She is completely LoonieTunes!
I think @sketch.and.jam is right. These birds can sound Loony!
I added this YouTube link to my post.
Oh my Loon-ness ! This sound is too crazy 😄
Looney, right?