One common way to say “crazy about” is マニア (mania: maniac, fanatic, someone who can’t get enough of something), which obviously comes straight from English. Here’s an example close to my heart:
お茶マニア (ochamania: crazy about tea)
Two other katakana “crazy” words have nothing to do with enthusiasm. Rather, the first is something like “hectic” or “chaotic”:
クレージー (kurējī: crazy)
Here’s a sample sentence:
忙しくって、クレージーだ。
Isogashiku tte, kurējī da.
Staying busy and crazy!!忙 (isoga(shii): busy)
プッツン (puttsun: weird, crazy, losing common sense, snapping; sound of a stretched string snapping)
This word represents the sound of a stretched string that snaps. At first, it literally referred to a string; now it means that someone has crossed a line into crazyland. When English speakers say, “And then he just snapped one day,” they mean プッツン. Nice to have a sound effect for craziness!
Note that プッチン (putchin) also works as onomatopoeia for snapping but does not share the extended meaning of craziness.
