The Koala in a Tree is an amazing and thoroughly satisfying sexual move. The Tree is a coat hanger. A woman is the Koala. After putting the woman in the "tree" the man then proceeds to have sex with whatever part of her body is closest to him. The woman is then taken down and put on a different "branch" where she is again mounted like a koala.
"Dude you'll never guess what my girlfriend let me do last night."
"the Koala in a Tree!!!!"
"Dude not cool. I use that coat hanger!"