Apparently within two years of a nuclear apocalypse, scorpions will become 5ft long. Why's it always the dangerous stuff that mutates into giant sizes? Leaving aside all the stuff about how diminished food sources would probably result in downward scaling (I'm no scientist, but that sounds a bit clever so I'm sticking with it), why not massive koalas or humungous gerbils?
I dunno, maybe all things become huge after the missiles land but we only see the dangerous ones.
Note to self: In the event of nuclear catastrophe, stick penis outside for a bit. Never know.