Fancy rats?
You can get them with dumbo ears:
Hairless:
Tailless:
You can also get rats with curly hair and whiskers, smooth hair, fairly long hair. There are so many different varieties of rats it's crazy. There are ones with bluish fur, and violety fur.
You may just have to look around a lot if you want something really special (like a blue on or a tailless)
Girls are more curious and daring.
Boys are mellow and bigger chickens (they also come with a nice set of balls)
I've only ever met one rat that has bitten me, other than that the billion rats I've handled have been little lovers.
If you have more questions feel free to ask, because I could talk about rats all day. I don't mind.