thats crazyy with 2 y's means that someone doesnt care at all.
friend: "Yo bro i got a new girl and she is so nice." Me: "Ohhh wow man thats crazyy."
a name to call your friends insted of stupid or idiot. it sounds better to say.
friend: "that girl/boy looks so ugly." Me: "Oi dont say it infront of her you retard."