Hey, Mickey, you're so fine... but you can only compete with other mice if you're packing some punch below the waist.
That's the message from a new study by evolutionary biologists in the journal American Naturalist, which finds that mice with the longest penises have the most luck with the ladies:
But... primates and bats didn't show a similar connection. And researchers aren't sure why certain male rats get such a benefit.
Size matters {MSNBC]