Originally posted by wolfsoul
I saw him at the petstore before I bought him though, and his testicles weren't sucked into his abdomen, they were out, and even bigger than my rats'! However, since I had him, they haven't...popped out...LOL. But the penis looks too far from the anus to be a female to me.

He's not a double rex, he's a nude ...He only has whiskers on his face. One of his parents was standard, the other other nude or hairless (The breeder didn't know).
Are you sure you did not mistake this rat for another? If it is indeed the same rat then I would take him to the vet. If he had testicles before and he has sucked them up, he is either sick or extremely stressed out. Again, I believe it's a doe. You can FOR SURE know if it's a male but pushing on the urethra, if a penis pops out then well, there's your answer.

And just to let you know, if both of his/her's parents were what you said, he cannot be a nude. A nude rat is a hairless born to two furred rats who carry the hairless gene, so he/she cannot be a nude. But if one of his parents is standard then he can't be a double rex anyway, but I wouldn't rely on any breeder who breeds to supply a petshop or snake food.

From the pictures, the rat looks like it has fuzz on his face, so that is why I said he looked double rex, OR he/she is a bad hairless. Obviously if one of the parents were standard, and since the hairless gene is recessive, he had to be a hairless, and his mother/father was a carrier, and one of the parents were hairless, or a hairless carrier.