We have a few of these odd pronunciations too
Star Wars had storm trapers until a couple of months ago - now they are storm troopers. Much earlier on we him spotting ships in fields and on hillsides that was mildly confusing until we realised he meant sheep. His mum and I still call them ships when we spot them in the car. I think one of them was just misheard at school and propagated amongst the class - whenever an incident occurs where a ball or other projectile comes into contact with his trouser area he shout "My peanuts".
( heyrudi has just found this setting, Mon 8 Apr 2013, 12:59, Reply)