Thanks guys!
They've grown extra adventurous lately, I guess they're bored with their basket of toys, 2 tunnels and 4 beds that they have because they've begun climbing my stuff. The other day I was watering the plants outside my window and looked in to see the two of them on my bed. I knocked on the window but they just ignored me so I had to come inside and get them. A few days later I discovered some little holes in my comforter. That's precisely why they're not allowed on the bed (and they do have 4 of their own). They also love to jump onto my desk chair and then onto my desk and then on top of their cage and climb on the stuff up there (their bin of food, drawer of hay, pile of rugs, etc.) I'm always worried that I'll startle them and they'll fall (especially after hearing about one of my classmate's cats that "supermanned" off the top of her cat tree and broke her leg) but they're so busy exploring that they just ignore me anyway.