I SO VERY----- I
I get freaked out even saying them out loud for pretend ..
I'd totally never use them..
though I'm surprised more wizards in the book don't..unless they're really hard to do accurately or something
In the Half Blood Prince, Harry tried to use the imperius curse on Snape after he killed Dumbeldore but Snape blocked it and told him he doesnt have the guts or talent to preform an unforgivable curse....so I assume it is difficult.
I'm not sure if I would use it or not, I joke all the time about "Avada Kedavra" To the muggels around a Harry Potter discussion...or squibs...and sometimes Huffelpuffs....
The other two I would most likely use. At the very least imperius just for fun. I could see me using Crucio is if I needed to.