His thoughts tumbled in his head, making and breaking alliances like underpants in a dryer without Cling Free.
LOL!
I like the one I saw once in another collection of metaphors:
She gave him a look you could pour on a waffle.
Jen... Perhaps you should ping the others in your group from the Hobbit Hole that are in that writing contest. Maybe this will provide a bit of inspiration!
I read a phrase once that has stuck in my mind ever since - "He swept from the room like a very long procession of one person". Actually, in context, it worked very well.