My sister and I used to do it when we were kids. It wasn't anything we chose to do, it just happened. There's one dream we were even convinced was a memory, it was only when we asked our brother about it that we realized it hadn't happened.

There was another where we both dreamed that two tall men in trench coats sneaked into our room and put me in the laundry basket at the foot of my bed. o.O

There were several dreams about a mansion and an evil witch. Then there was one dream where we just brushed the edges of each others dreams. We both are visiting a white plantation house. We both walk into a small dark bathroom. All we can see is the mirror over the sink. When I look into the mirror I see a woman with blue eyes and red-gold hair wearing an elaborate dress. When my sister looks into the mirror she sees a small dark haired woman in leather armor. (We thought it was funny how we each saw what the other one expected to see, she's more girly than I am. She has blonde hair and blue eyes, I have brown hair and green eyes, she's also like 5 inches taller than me.) Later I'm walking past a room with the door cracked open, there's a large bed. I can see a girl inside who turns into a black cat and lays on the bed.
My sister goes into a bedroom because she sees a girl she knew from middle school going inside. The girl turns into a black cat and lays down on the bed.
There's a tunnel full of doors beneath the house. I find an open door, there's a room full of frogs with a pond in the middle.
She's walking down a tunnel full of doors. There's one cracked open, the interior is full of frogs in a pond. She spends the rest of the dream trying to catch frogs.


It hasn't happened since. Guess we grew apart that way.