Me and a friend (who is a member here) were playing a cross platform MMORPG and I had her teleport to my house. She was swimming before I invited her and instead of appearing on land, standing, she was diving (She must have been searching for loot). On the same note, I teleported to my friend in a cave and was swimming in the floor.
And one last one out of the same game. I had a house where everyone would ice skate instead of walking. A friend wanted to use my house real quick to farm for money. When I changed my house, I was still skating, but on dirt. I was also invincible to my friend's sword while he was farming. Sort of like god-mod ice skates or something.