Don't know about bats, but years ago, my kids kept a few hooded rats, like this one.

Notice his balls, if you will. Well, my kid's rats eventually grew balls about 4 times that size. No kidding.

It was absolutely disgusting, really. The boys liked to carry them around on their shoulders, or the visor of their baseball caps. When the stupid things (and yes I do mean *STUPID* - those creatures would eat anything, including paper and plastic and scouring pads) would face the 'wrong way', all you'd see was these humungous pink testes ballooning out on either side of the loooong naked creepy-looking tail.

At one point I tried to design a little diaper for them, for modesty's sake   ;-)

WHat I'm wondering is - if we hadn't kept thier cage so close to our one and only female rat, no doubt driving them NUTS (in a VERY BIG way) with the scent of something they couldn't get at - would their balls have grown so large? Would they have been spared the urge to chomp down everything in sight, edible or no?

Hey, does anyone here really give a rat's ass either way?