1.) The Cell Phone. I just went into the bathroom here at work and someone who shall remain nameless was talking on their cell phone while on the crapper. Ok, look. It's a crapper. Not a phone booth. You're welcome to take your dump, take a pee too if it floats your boat, do all of that good stuff. But please, no cell phone conversations. That's why God invented voicemail. This is trumped only by those people (almost always wearing business suits, it seems) who actually talk on the cellphone while using the urinal. While I applaud their dexterity, I'm sorry, but that's just not kosher.
2.) The Gameboy. This was a first, actually. A few days ago while using the facilities in the bathroom at work, someone in one of the stalls let out a terrific braaaap - that strident bugle call announcing the commencement of the activities. Fine. A moment later, though, I heard Gameboy music start up. It was periodically punctuated by the sound of further bodily functions, and when I flushed the urinal and they realized they weren't alone in the bathroom, they turned the music down. Note to self: never borrow anyone's Gameboy, ever. EVER.