I discovered this the other day and thought I'd share. My fiance got a real kick out of it.
I've been keeping most of my mice in small rubbermaid containers to make it easier to move them into my new apartment. The other day I went into my spare bedroom where I keep the mice and it smelled TERRIBLE even though I'd just cleaned everybody's tanks. I couldn't figure out why until I saw one of my big male bucks sitting on top of his tub looking at me.
Turns out he had chewed out of the top (he can reach the top where I've drilled holes into the lid by standing on top of his plastic hut house) and went over to the tub next to him which also contained a male and was peeing on the lid of the other males tub. It was driving the trapped male crazy so he was in return marking his entire cage.... it was a pee off! :roll:
Needless to say I put the chewer in a bigger tub where he can't reach the air holes and moved him as far away from males as possible. :lol: